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Simultaneous: A Novel
A mind-bending speculative thriller where past lives collide with present danger and the
truth follows you across every timeline.
Federal agent Grant Lukather works in a shadow division of Homeland Security known only as Predictive Analytics, a unit trained to detect catastrophic events before they occur. When an anonymous tip warns of a deadly explosion in New Mexico, the case quickly spirals into something no model or agent has ever prepared for. Grant’s search leads him to Sarah Newcomb, a therapist whose unusual method of past-life
hypnosis has revealed something a pattern connecting her patients to crimes happening right now.
As Grant investigates a disturbing copycat murder in Colorado, the two uncover a phenomenon that stretches across multiple states, multiple timelines, and multiple versions of the same lives. With the help of Sarah’s most troubled patient, they form an unlikely trio navigating shifting realities, fractured memories, and a killer who seems to exist everywhere at once.
Time is folding in on itself. Identities are merging. And every choice they make in one life echoes dangerously into the next.
From the Oscar-nominated screenwriter of "Arrival," Simultaneous
Stunning reveals and reality-bending twists
A tense, race-against-time serial-killer mystery
A supernatural edge rooted in fate, free will, and the weight of past lives
Characters whose connections deepen across lifetimes
Perfect for fans of early Dean Koontz, Blake Crouch, and mind-twisting supernatural thrillers. If your past is chasing you, how far can you run when it knows your future?
“A twisty, mind-bending thriller that will keep you guessing until the final gut punch.” —Leigh Bardugo
truth follows you across every timeline.
Federal agent Grant Lukather works in a shadow division of Homeland Security known only as Predictive Analytics, a unit trained to detect catastrophic events before they occur. When an anonymous tip warns of a deadly explosion in New Mexico, the case quickly spirals into something no model or agent has ever prepared for. Grant’s search leads him to Sarah Newcomb, a therapist whose unusual method of past-life
hypnosis has revealed something a pattern connecting her patients to crimes happening right now.
As Grant investigates a disturbing copycat murder in Colorado, the two uncover a phenomenon that stretches across multiple states, multiple timelines, and multiple versions of the same lives. With the help of Sarah’s most troubled patient, they form an unlikely trio navigating shifting realities, fractured memories, and a killer who seems to exist everywhere at once.
Time is folding in on itself. Identities are merging. And every choice they make in one life echoes dangerously into the next.
From the Oscar-nominated screenwriter of "Arrival," Simultaneous
Stunning reveals and reality-bending twists
A tense, race-against-time serial-killer mystery
A supernatural edge rooted in fate, free will, and the weight of past lives
Characters whose connections deepen across lifetimes
Perfect for fans of early Dean Koontz, Blake Crouch, and mind-twisting supernatural thrillers. If your past is chasing you, how far can you run when it knows your future?
“A twisty, mind-bending thriller that will keep you guessing until the final gut punch.” —Leigh Bardugo
279 pages, Kindle Edition
First published October 28, 2025
99 people are currently reading
9260 people want to read
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Displaying 1 - 30 of 144 reviews
December 10, 2025
Holy cow! An ingenious new novel in the speculative thriller subgenre, Simultaneous quickly grabbed me and didn’t let go. With a fast-paced storyline, plenty of action-packed scenes, and a trio of root-for-able narrators, the whole combination was an utter home run. You see, I’ve always loved a good time-loop storyline, and Mr. Heisserer was at the top of his game when he crafted this one. Somehow oddly believable yet also the definition of speculative fiction, I was fully immersed in the story all while the truth was kept just out of reach. After all, thanks to a series of truly unguessable twists, just when I thought I had it all figured out, the rug was pulled out from under my feet in several brilliant, sharp tugs. Propulsive and mind-bending, the twisty plotting had me on the edge of my seat from beginning to end of this impressive debut.
All said and done, despite the complexity of the storyline, which took some concentration to follow at times, I fell for this tale head over heels. Thought-provoking and poignant but also adrenaline-fueled and thrilling, it was not only perfect for fans of Dark Matter and Wrong Place Wrong Time, but it was also incredibly unique. I mean, diving deep into the theory of reincarnation, it had me pondering what it might mean for my soul after I die. What really got me, however, were the characters. Fully fleshed out and with deep backstories for each, I felt as if I really knew all of the POVs. Everything I love in a compelling persona, they were complex, nuanced, and genuinely flawed. So if you’re looking for an entirely different kind of a novel, give this one a go. After all, that open-ended conclusion alone made this one shine. Rating of 5 stars.
SYNOPSIS:
Federal agent Grant Lukather works for an unknown department of Homeland Security called Predictive Analytics. They look for patterns in tips and chatter to prevent a terrorist event before it happens. One of these calls, about a possible explosion in New Mexico, leads Grant to a case with unimaginable consequences.
He meets Sarah Newcomb, a therapist who uses past-life hypnosis in her treatment but has recently stumbled upon a phenomenon that seems to defy logic. Grant follows this thread to another crime: a copycat killer case in Colorado. With the help of one of Sarah’s patients, they embark upon an investigation that spans multiple states, timelines, and consciousnesses. With limited time and only a tenuous grasp of how this phenomenon works, the unlikely trio are in a race for their lives―past, present, and future.
Thank you to Eric Heisserer and Flatiron Books for my complimentary copy. All opinions are my own.
PUB DATE: October 28, 2025
Content warning: wildfire, murder, knife and gun violence, suicide, mention of: explosion, domestic abuse
All said and done, despite the complexity of the storyline, which took some concentration to follow at times, I fell for this tale head over heels. Thought-provoking and poignant but also adrenaline-fueled and thrilling, it was not only perfect for fans of Dark Matter and Wrong Place Wrong Time, but it was also incredibly unique. I mean, diving deep into the theory of reincarnation, it had me pondering what it might mean for my soul after I die. What really got me, however, were the characters. Fully fleshed out and with deep backstories for each, I felt as if I really knew all of the POVs. Everything I love in a compelling persona, they were complex, nuanced, and genuinely flawed. So if you’re looking for an entirely different kind of a novel, give this one a go. After all, that open-ended conclusion alone made this one shine. Rating of 5 stars.
SYNOPSIS:
Federal agent Grant Lukather works for an unknown department of Homeland Security called Predictive Analytics. They look for patterns in tips and chatter to prevent a terrorist event before it happens. One of these calls, about a possible explosion in New Mexico, leads Grant to a case with unimaginable consequences.
He meets Sarah Newcomb, a therapist who uses past-life hypnosis in her treatment but has recently stumbled upon a phenomenon that seems to defy logic. Grant follows this thread to another crime: a copycat killer case in Colorado. With the help of one of Sarah’s patients, they embark upon an investigation that spans multiple states, timelines, and consciousnesses. With limited time and only a tenuous grasp of how this phenomenon works, the unlikely trio are in a race for their lives―past, present, and future.
Thank you to Eric Heisserer and Flatiron Books for my complimentary copy. All opinions are my own.
PUB DATE: October 28, 2025
Content warning: wildfire, murder, knife and gun violence, suicide, mention of: explosion, domestic abuse
May 21, 2025
Grant is a Homeland Security agent in the department of Predictive Analytics, which investigates projections of terrorism to stop attacks before they happen. Sarah is a past-life therapist who accesses her patients’ previous incarnations to help them heal. Marigold is a patient whose “past” body actually lives in the present. In Simultaneous by Eric Heisserer, these three unlikely companions must work together to catch a serial killer and prevent the upheaval of the world.
This book felt too short. As soon as the past-lives idea started getting really interesting, the novel ended. There were a considerable number of moments that could have been drawn out longer, and there was a lot about the characters that was either left unexplored or discussed too shortly. I really liked the ideas behind the story and the characters, and I think they could play off each other well, but they were never given enough space to do so.
Eric Heisserer is a screenwriter known for his work on the film Arrival and the series Shadow and Bone, among other successful productions. I believe Simultaneous would work better as a screenplay. I think the subtlety of the characters’ feelings about each other and the world would be better conveyed through visual acting. As it is, with the characters’ emotions and motivations written out in unambiguous therapy lingo and explicit psychoanalysis, the characterization feels too heavy-handed. The problem isn’t necessarily with the characters intellectualizing their feelings but with the narrator stating it all to us outright.
The characters clash, but not as much as I think they should. They connect with each other, but not at a pace that feels natural. They reconcile, but only because they all end up speaking and thinking the same way. I know the author has good ideas about who Grant and Sarah are, but I think those ideas could be more specific and subtle; they could also be explored more in quieter scenes that help us to learn gradually who the characters are, not just by how they speak or how the narrator describes them but by the way they act on their own and around each other.
Marigold was unfortunately left as a plot device, the introduction to the idea of shared souls and the medium through which it is used to predict the future whenever convenient. I would have liked to see more of her.
I wish the writing had more flair and creative nuance. The many interesting scenes in this book could be elevated significantly by greater attention to atmosphere. I never felt the tone change when it should have, most notably when the trio started their pursuit of the Ash Killer.
I like when speculative thrillers are disturbing, morally contentious, and even convoluted. I like them to take a concept with concerning implications and then push it to its limits. I think they should make a statement, or at least make my heart race. Every part of Simultaneous unfolded logically and predictably. It was a fast-paced and readable story, but it didn’t leave me with any food for thought. The concept is very intriguing, but Simultaneous doesn’t fulfill its potential.
2/5
This book felt too short. As soon as the past-lives idea started getting really interesting, the novel ended. There were a considerable number of moments that could have been drawn out longer, and there was a lot about the characters that was either left unexplored or discussed too shortly. I really liked the ideas behind the story and the characters, and I think they could play off each other well, but they were never given enough space to do so.
Eric Heisserer is a screenwriter known for his work on the film Arrival and the series Shadow and Bone, among other successful productions. I believe Simultaneous would work better as a screenplay. I think the subtlety of the characters’ feelings about each other and the world would be better conveyed through visual acting. As it is, with the characters’ emotions and motivations written out in unambiguous therapy lingo and explicit psychoanalysis, the characterization feels too heavy-handed. The problem isn’t necessarily with the characters intellectualizing their feelings but with the narrator stating it all to us outright.
The characters clash, but not as much as I think they should. They connect with each other, but not at a pace that feels natural. They reconcile, but only because they all end up speaking and thinking the same way. I know the author has good ideas about who Grant and Sarah are, but I think those ideas could be more specific and subtle; they could also be explored more in quieter scenes that help us to learn gradually who the characters are, not just by how they speak or how the narrator describes them but by the way they act on their own and around each other.
Marigold was unfortunately left as a plot device, the introduction to the idea of shared souls and the medium through which it is used to predict the future whenever convenient. I would have liked to see more of her.
I wish the writing had more flair and creative nuance. The many interesting scenes in this book could be elevated significantly by greater attention to atmosphere. I never felt the tone change when it should have, most notably when the trio started their pursuit of the Ash Killer.
I like when speculative thrillers are disturbing, morally contentious, and even convoluted. I like them to take a concept with concerning implications and then push it to its limits. I think they should make a statement, or at least make my heart race. Every part of Simultaneous unfolded logically and predictably. It was a fast-paced and readable story, but it didn’t leave me with any food for thought. The concept is very intriguing, but Simultaneous doesn’t fulfill its potential.
2/5
May 26, 2025
WOW- I was intrigued from the first page until the ending. Imagine that there are only so many available souls and recent history has increased the population so substantially that the should cannot keep up. Therefore one soul occupies multiple bodies...simultaneously....hence the title. So this is used to solve murder and multiple murder cases, or at least to try. The characters are; Sarah, a past lives therapist who has stumbled upon a simultaneous lives patient. Marigold, her patient, and Brian, with whom Marigold shares a soul. Lastly, Grant, a homeland security agent who has gotten involved with the case.
This book is big on plot, less so on character building. Most of the narrative is spent in plot points and driving the narrative forward. At no point in the book could I guess what was going to happen next! I think some people will likely hate the ending, me, I LOVED it.
This book is great for those that like- action packed adventure stories, speculative thrillers, and crime fiction. I found the dialogue and the plot to be very accessible and not overly scientific, nor did it get bogged down in technical vocabulary. I could not put this down and read it from start to finish in one sitting.
I received this book for free as an ARC from Flat Iron Publishing and I voluntarily wrote this review.
This book is big on plot, less so on character building. Most of the narrative is spent in plot points and driving the narrative forward. At no point in the book could I guess what was going to happen next! I think some people will likely hate the ending, me, I LOVED it.
This book is great for those that like- action packed adventure stories, speculative thrillers, and crime fiction. I found the dialogue and the plot to be very accessible and not overly scientific, nor did it get bogged down in technical vocabulary. I could not put this down and read it from start to finish in one sitting.
I received this book for free as an ARC from Flat Iron Publishing and I voluntarily wrote this review.
November 10, 2025
Grant, a Federal agent from the Predictive Analytics department teams up with Sarah, a unconventional therapist, to stop a killer, along with help from Sarah's patient Marigold. This is the very definition of a speculative thriller. In order to have a great time with this one, you need to accept the phenomenon as presented and then hang on! What phenomenon? You'll have to read to find out...
The pace with this one is SWIFT and the momentum only increases as the story continues. There's just enough back-story to get a full sense of the characters without it bogging down the suspense. Perspectives shift frequently within chapters and with talk of timelines and altering future events you NEED to pay attention. I was expecting a science fiction aspect and this is more metaphysical but if you buy in, it will definitely break your brain as you consider the paradoxical nature of the situation. There are bursts of intense action that switch back and forth between multiple events happening simultaneously which had me flying through pages!
The audiobook is SOOOO STINKIN GOOD! Ray Porter narrates the majority of the book and his performance is outstanding! His volume, pitch and pace increased with emotions such as excitement and fear and then decreased with quieter meaningful and reflective moments. Marin Ireland and Stephanie Sheh were equally fantastic conveying the taut and terrifying situation. The audiobook truly elevated the entire reading experience to a cinematic one, which is no wonder since Eric Heisserer is a screenwriter!
Okay folks, strap in and hold tight because SIMULTANEOUS is a gripping high stakes edge-of-your-seat race against time to stop a killer. Definitely settle in to read with no distractions because you'll want to finish this mind-bending thrill ride in one sitting!
The pace with this one is SWIFT and the momentum only increases as the story continues. There's just enough back-story to get a full sense of the characters without it bogging down the suspense. Perspectives shift frequently within chapters and with talk of timelines and altering future events you NEED to pay attention. I was expecting a science fiction aspect and this is more metaphysical but if you buy in, it will definitely break your brain as you consider the paradoxical nature of the situation. There are bursts of intense action that switch back and forth between multiple events happening simultaneously which had me flying through pages!
The audiobook is SOOOO STINKIN GOOD! Ray Porter narrates the majority of the book and his performance is outstanding! His volume, pitch and pace increased with emotions such as excitement and fear and then decreased with quieter meaningful and reflective moments. Marin Ireland and Stephanie Sheh were equally fantastic conveying the taut and terrifying situation. The audiobook truly elevated the entire reading experience to a cinematic one, which is no wonder since Eric Heisserer is a screenwriter!
Okay folks, strap in and hold tight because SIMULTANEOUS is a gripping high stakes edge-of-your-seat race against time to stop a killer. Definitely settle in to read with no distractions because you'll want to finish this mind-bending thrill ride in one sitting!
August 27, 2025
I’m so disappointed I want to cry. Hence, 1 star.
I loved the movie ARRIVAL and not just because I love Jeremy Renner and Amy Adams and the story on which it was based. I thought it was extremely well written and faithful to a book that was probably hard to be faithful to. Which is to say, it somehow executed a difficult premise well. So now I see that the screenwriter has written a novel? Yes, I am going to jump on getting that from Booktrovert/NetGalley.
When I’ve read screenwriters-turned-authors in the past they tend to be the kind of fast-paced popcorn books I love. And the premise was giving Blake Crouch. The short version is this: a government agent investigates predictions of major crimes; a past-lives therapist has a patient making such predictions. But are they past lives… or are they simultaneous lives?
A speculative-fiction book like this goes one of two ways: you buy into it and enjoy the ride or you have no fucking idea what’s going on and you don’t think the author does either. This is the latter for me. It’s the kind of book where the main characters are literally always going, “This makes no sense” and “My brain hurts.” Well, yeah, same. So, IDK, make it hurt less??? I have to compare it to Blake Crouch — that man breaks my brain in the best way. It can be total bullshit and far-fetched… but I feel smart when I’m done, not confused.
Maybe it’s because I already knew a screenwriter wrote this, but it really did read like a script. Exposition dumps, monologues… and it was often like you’re reading stage directions for the setting. I can give you an example: “A new vehicle pulls into the garage. A minivan, its rear window jammed with clothes, children’s toys, and small boxes. As if driven by a hoarder.” These are the kinds of half-sentences you’d see in a script, no? I think it’s the third-person present tense that sucks too. And too much distance from the characters… again, these are not the kind of characters you get from BC books. There were great concepts here, I could see what was being attempted… but it did not work for me at all. OK… and now I’m gonna get really cynical here and be like, Was this a long-unproduced screenplay that was turned into a book? It has to be.
It made me mad. And then near the end someone actually said “I sound like a character in a time-travel movie now.” So I got madder. Read (or re-read for the 3rd time, if you’re me) RECURSION instead.
I loved the movie ARRIVAL and not just because I love Jeremy Renner and Amy Adams and the story on which it was based. I thought it was extremely well written and faithful to a book that was probably hard to be faithful to. Which is to say, it somehow executed a difficult premise well. So now I see that the screenwriter has written a novel? Yes, I am going to jump on getting that from Booktrovert/NetGalley.
When I’ve read screenwriters-turned-authors in the past they tend to be the kind of fast-paced popcorn books I love. And the premise was giving Blake Crouch. The short version is this: a government agent investigates predictions of major crimes; a past-lives therapist has a patient making such predictions. But are they past lives… or are they simultaneous lives?
A speculative-fiction book like this goes one of two ways: you buy into it and enjoy the ride or you have no fucking idea what’s going on and you don’t think the author does either. This is the latter for me. It’s the kind of book where the main characters are literally always going, “This makes no sense” and “My brain hurts.” Well, yeah, same. So, IDK, make it hurt less??? I have to compare it to Blake Crouch — that man breaks my brain in the best way. It can be total bullshit and far-fetched… but I feel smart when I’m done, not confused.
Maybe it’s because I already knew a screenwriter wrote this, but it really did read like a script. Exposition dumps, monologues… and it was often like you’re reading stage directions for the setting. I can give you an example: “A new vehicle pulls into the garage. A minivan, its rear window jammed with clothes, children’s toys, and small boxes. As if driven by a hoarder.” These are the kinds of half-sentences you’d see in a script, no? I think it’s the third-person present tense that sucks too. And too much distance from the characters… again, these are not the kind of characters you get from BC books. There were great concepts here, I could see what was being attempted… but it did not work for me at all. OK… and now I’m gonna get really cynical here and be like, Was this a long-unproduced screenplay that was turned into a book? It has to be.
It made me mad. And then near the end someone actually said “I sound like a character in a time-travel movie now.” So I got madder. Read (or re-read for the 3rd time, if you’re me) RECURSION instead.
October 25, 2025
A timey wimey wibbley wobbley story about past lives that broke my brain. But… to be fair, the author Eric Heisserer wrote the screenplay for Arrival which also broke my brain so how could I not love Simultaneous?!
To make it even better, I listened to the audiobook which was performed by my favorite narrator, Ray Porter. He was, as usual, AMAZING!
I think speculative thrillers are becoming my favorite genre!
Grant, a federal agent with the Homeland Security Department of Predictive Analytics joins up with civilians Sarah, a past-life therapist and her client Marigold.
Sarah’s theory about past-lives is mind blowing enough as it is, but then pit them against a possible person committing multiple homicides, and you have a crazy fast paced thriller that makes your head spin in all of the best ways.
I took my time with this book for two reasons. One, I didn’t want to miss a thing. There were a few times when I would rewind just to make sure I was understanding what had just happened. And second, it was Ray Porter and I didn’t want the story to end. (And yes, I’m having an audiobook hangover!)
The ending seemed open to me and I would love to explore a sequel. Fingers crossed!
*Thanks so much to MacMillan Audio and to NetGalley for the gifted advanced audiobook!*
To make it even better, I listened to the audiobook which was performed by my favorite narrator, Ray Porter. He was, as usual, AMAZING!
I think speculative thrillers are becoming my favorite genre!
Grant, a federal agent with the Homeland Security Department of Predictive Analytics joins up with civilians Sarah, a past-life therapist and her client Marigold.
Sarah’s theory about past-lives is mind blowing enough as it is, but then pit them against a possible person committing multiple homicides, and you have a crazy fast paced thriller that makes your head spin in all of the best ways.
I took my time with this book for two reasons. One, I didn’t want to miss a thing. There were a few times when I would rewind just to make sure I was understanding what had just happened. And second, it was Ray Porter and I didn’t want the story to end. (And yes, I’m having an audiobook hangover!)
The ending seemed open to me and I would love to explore a sequel. Fingers crossed!
*Thanks so much to MacMillan Audio and to NetGalley for the gifted advanced audiobook!*
May 21, 2025
I recieved a copy of this ARC and am leaving this review voluntarily.
This is my first book with Eric Heisserer and I'm very surprised how good this book was! It took your typical serial killer case and put a shocking and interesting twist on it. It incorporated themes of cult like killers that use the power of reincarnation as a method of control and manipulation. It really reminded me of the Stephen King book Doctor Sleep with the soul snatching of young victims mixed with similar themes of dream escaping like from the Netflix show Behind Her Eyes that explored dreaming and escaping your body to another. While it started off slow, middle to the end was intensely action packed that will leave you wanting more and leave you questioning what are the limits possible within one's mind.
This is my first book with Eric Heisserer and I'm very surprised how good this book was! It took your typical serial killer case and put a shocking and interesting twist on it. It incorporated themes of cult like killers that use the power of reincarnation as a method of control and manipulation. It really reminded me of the Stephen King book Doctor Sleep with the soul snatching of young victims mixed with similar themes of dream escaping like from the Netflix show Behind Her Eyes that explored dreaming and escaping your body to another. While it started off slow, middle to the end was intensely action packed that will leave you wanting more and leave you questioning what are the limits possible within one's mind.
This entire review has been hidden because of spoilers.
November 3, 2025
A dose of science fiction once in a while helps to enhance brain creativity, function, and efficiency
November 10, 2025
Felt like an episode of the x-files
July 2, 2025
2.9
maybe I just don't like thrillers 🤷♂️
kinda interesting concept that I feel was under explored/developed/explained
very fast-paced, easy read, had potential but overall meh
ending had my eyes rolling eternally
maybe I just don't like thrillers 🤷♂️
kinda interesting concept that I feel was under explored/developed/explained
very fast-paced, easy read, had potential but overall meh
ending had my eyes rolling eternally
August 29, 2025
Thank you to Flat Iron Books for the Advanced Reader Copy! Man, this one HOOKED ME. such a fascinating premise and it felt very unique in its story telling! The first half was building up the story and groundwork and then the last half was FAST PACED AS HELL. Every chapter had a new revelation or piece of the missing puzzle. There was a small storyline that I think didn’t get wrapped up or clarified for me, but given how the ending was a little open ended I figured it might be because there will be another in a series? Unclear but I hope there is more!! Fans or dark matter will like this one!
September 8, 2025
Oscar-nominated screenwriter Eric Heisserer delivers a powerful debut with
Simultaneous
, a fantastic speculative thriller. With its mind-bending concept, this novel had me hooked from the start and didn't let go until the very last page.
Federal agent Grant Lukather works for an unknown department of Homeland Security called Predictive Analytics. They look for patterns in tips and chatter to prevent a terrorist event before it happens. One of these calls, about a possible explosion in New Mexico, leads Grant to a case with unimaginable consequences.
He meets Sarah Newcomb, a therapist who uses past-life hypnosis in her treatment but has recently stumbled upon a phenomenon that seems to defy logic. Grant follows this thread to another crime: a copycat killer case in Colorado. With the help of one of Sarah’s patients, they embark upon an investigation that spans multiple states, timelines, and consciousnesses. With limited time and only a tenuous grasp of how this phenomenon works, the unlikely trio are in a race for their lives—past, present, and future.
Several factors draw me to debut novels, and a big one is when the author is already impressed me with their work in film or television. That's what drew me to Simultaneous by Eric Heisserer. He's the Oscar-nominated screenwriter behind award-winning Arrival , as well as Bird Box, A Nightmare on Elm Street (2010), The Thing (2011), Final Destination 5 , Extinction, Bloodshot , Shadow and Bone, and more. With a resume such as that, I had high expectations, and he absolutely delivered. The premise of Simultaneous immediately hooked me, and the story kept me in its grasp from the first chapter to the last page.
Imagine the world only has a limited number of souls, but the increasing population has grown so fast that souls are now shared, one soul occupying multiple bodies simultaneously. Heisserer uses this premise as his characters attempt to solve a murder, or multiple murders. This unique story and Heisserer's ability to draw you into said story, made Simultaneous one of those books I couldn't put down.
Heisserer builds a tremendous plot, but doesn't neglect his characters, while not fully. From Grant, a Homeland Security agent, to Sarah, a therapist, and her patient Marigold (who shares a should with a man named Brian), the cast is distinct. While the story's momentum takes center stage, these characters still leave a last impression when all is said and done.
Simultaneous is a thrilling, fast-paced speculative crime fiction packed with twists, a truly unique premise, and just the right touch of humor. Eric Heisserer's debut novel is bold, mind-bending, and most of all a must-read for fans of the genre. Given how much I have loved his work on screen over the years, it's no surprise this book hit the mark for me.
Simultaneous hits bookstores everywhere on October 28, 2025 from Flatiron Books. The audiobook, narrated by Marin Ireland, Ray Porter & Stephanie Sheh, is available for preorder via Libro.fm! Eric Heisserer joins the Capes and Tights Podcast on September 24 to discuss Simultaneous and more!
NOTE: We received an advance copy of Simultaneous from the publisher. Opinions are our own.
Federal agent Grant Lukather works for an unknown department of Homeland Security called Predictive Analytics. They look for patterns in tips and chatter to prevent a terrorist event before it happens. One of these calls, about a possible explosion in New Mexico, leads Grant to a case with unimaginable consequences.
He meets Sarah Newcomb, a therapist who uses past-life hypnosis in her treatment but has recently stumbled upon a phenomenon that seems to defy logic. Grant follows this thread to another crime: a copycat killer case in Colorado. With the help of one of Sarah’s patients, they embark upon an investigation that spans multiple states, timelines, and consciousnesses. With limited time and only a tenuous grasp of how this phenomenon works, the unlikely trio are in a race for their lives—past, present, and future.
Several factors draw me to debut novels, and a big one is when the author is already impressed me with their work in film or television. That's what drew me to Simultaneous by Eric Heisserer. He's the Oscar-nominated screenwriter behind award-winning Arrival , as well as Bird Box, A Nightmare on Elm Street (2010), The Thing (2011), Final Destination 5 , Extinction, Bloodshot , Shadow and Bone, and more. With a resume such as that, I had high expectations, and he absolutely delivered. The premise of Simultaneous immediately hooked me, and the story kept me in its grasp from the first chapter to the last page.
Imagine the world only has a limited number of souls, but the increasing population has grown so fast that souls are now shared, one soul occupying multiple bodies simultaneously. Heisserer uses this premise as his characters attempt to solve a murder, or multiple murders. This unique story and Heisserer's ability to draw you into said story, made Simultaneous one of those books I couldn't put down.
Heisserer builds a tremendous plot, but doesn't neglect his characters, while not fully. From Grant, a Homeland Security agent, to Sarah, a therapist, and her patient Marigold (who shares a should with a man named Brian), the cast is distinct. While the story's momentum takes center stage, these characters still leave a last impression when all is said and done.
Simultaneous is a thrilling, fast-paced speculative crime fiction packed with twists, a truly unique premise, and just the right touch of humor. Eric Heisserer's debut novel is bold, mind-bending, and most of all a must-read for fans of the genre. Given how much I have loved his work on screen over the years, it's no surprise this book hit the mark for me.
Simultaneous hits bookstores everywhere on October 28, 2025 from Flatiron Books. The audiobook, narrated by Marin Ireland, Ray Porter & Stephanie Sheh, is available for preorder via Libro.fm! Eric Heisserer joins the Capes and Tights Podcast on September 24 to discuss Simultaneous and more!
NOTE: We received an advance copy of Simultaneous from the publisher. Opinions are our own.
September 29, 2025
Super duper DUPER confusing but entertaining. Don’t think I’ll read the sequel the author is CLEARLY moving towards
November 3, 2025
Holy crap, this was so good! Absolutely my kind of book! Plus Ray Porter narrates, you guys 😍 I hope hope hope there's a second one, just keep em coming!
September 16, 2025
WOW!! This was a fantastic book. I was hooked from the beginning by the seamless blend of cop drama and mystery and sci-fi and serial killer hunt. There are strong and well-developed characters characters and really thought-provoking and original concepts.
But what really earned the wow was the ending! In rapid-fire succession, several things happened that I did not see coming AT ALL, queuing up the next book. I had no idea this would turn out to be a multi-book storyline, and am absolutely delighted by it because this is a world I would happily return to again and again.
Heisserer has done a phenomenal job creating a universe that is original with nods to concepts that you've encountered before. But what works so well here is the facility with which he manages to manipulate them in wholly original and new ways into a whole that is infinitely more than the sum of its parts. This was a fantastic story, and I really hope the next book comes along very quickly!
Thanks to Libro.fm and their advance librarian review program for my obligation-free review copy.
But what really earned the wow was the ending! In rapid-fire succession, several things happened that I did not see coming AT ALL, queuing up the next book. I had no idea this would turn out to be a multi-book storyline, and am absolutely delighted by it because this is a world I would happily return to again and again.
Heisserer has done a phenomenal job creating a universe that is original with nods to concepts that you've encountered before. But what works so well here is the facility with which he manages to manipulate them in wholly original and new ways into a whole that is infinitely more than the sum of its parts. This was a fantastic story, and I really hope the next book comes along very quickly!
Thanks to Libro.fm and their advance librarian review program for my obligation-free review copy.
August 21, 2025
Simultaneous is a science fiction thriller written by Eric Heisserer, the Oscar-nominated writer of Arrival, as well as Bird Box, Lights Out, Final Destination 5 and other films. It tells the story of Grant Lukather, a federal agent with the Predictive Analytics department of Homeland Security, who investigates a serial killer with the help of Sarah, a past-lives therapist, and Marigold, one of her clients.
The book is predicated on the thought that there are only a limited number of souls in the world, fewer than the number of people due to population explosion. Because of this, various people must share the same soul. Marigold is one of those people and she shares a soul (in the present time) with a police officer who is investigating the killer. Our three lead characters work together to try and stop killings that Marigold knows are set to occur.
Simultaneous is a short, fast-paced book, fun from start to finish with great plot twists. I chose to listen to the audiobook upon learning that two of the three narrators were Marin Ireland and Ray Porter (both favorites of mine). Ray Porter provides almost all of the narration, with Marin Ireland and Stephanie Sheh relegated to just a few short chapters. While I regretted that there wasn’t more for Marin to read, I enjoyed the work of each of them.
I tend to do better with science fiction movies than books and there were times that I chose to go back and listen to sections a second time out of fear of getting lost in the plot. This tended to be more the result of not keeping minor characters straight in my head versus finding the book to be too technical (my normal issue with science fiction). Having to repeat a few parts didn’t impact my overall enjoyment of the book and I will highly recommend it to friends who like the genre.
I must close with saying that Simultaneous would make a great screenplay. Thanks to Macmillan Audio and NetGalley for providing me the opportunity to read Simultaneous. The above opinions are my own.
The book is predicated on the thought that there are only a limited number of souls in the world, fewer than the number of people due to population explosion. Because of this, various people must share the same soul. Marigold is one of those people and she shares a soul (in the present time) with a police officer who is investigating the killer. Our three lead characters work together to try and stop killings that Marigold knows are set to occur.
Simultaneous is a short, fast-paced book, fun from start to finish with great plot twists. I chose to listen to the audiobook upon learning that two of the three narrators were Marin Ireland and Ray Porter (both favorites of mine). Ray Porter provides almost all of the narration, with Marin Ireland and Stephanie Sheh relegated to just a few short chapters. While I regretted that there wasn’t more for Marin to read, I enjoyed the work of each of them.
I tend to do better with science fiction movies than books and there were times that I chose to go back and listen to sections a second time out of fear of getting lost in the plot. This tended to be more the result of not keeping minor characters straight in my head versus finding the book to be too technical (my normal issue with science fiction). Having to repeat a few parts didn’t impact my overall enjoyment of the book and I will highly recommend it to friends who like the genre.
I must close with saying that Simultaneous would make a great screenplay. Thanks to Macmillan Audio and NetGalley for providing me the opportunity to read Simultaneous. The above opinions are my own.
November 28, 2025
Simultaneous follows Grant Lukather, a Homeland Security agent, and Sarah Newcomb, a therapist who uses past-life hypnosis, as they stumble into a mystery where some souls live multiple lives at the same time and someone is using that strange truth to cause real-world harm. It’s a twisty mix of sci-fi and suspense, and that vibe set the perfect stage for my audiobook experience. I listened to this one on audio and I was so happy to hear two of my favorite narrators, Ray Porter and Marin Ireland, guiding me through this wild ride. It honestly felt like watching a movie in my head, which makes total sense since Eric Heisserer wrote one of my favorite films, Arrival.
I loved how the story balanced action and adventure with just enough character moments to make me care. I probably could have handled a little more time getting to know them on a deeper level, but the pace was so snappy and engaging that I stayed hooked the entire time. The audiobook is only about seven hours and it is perfect for a marathon day of getting things done. I listened while prepping Thanksgiving dinner and there were moments where I actually had to stop and focus on my recipe so I didn’t mess anything up for my family.
I’m giving this four stars for the adventure, the fun, and the totally unique premise that kept me listening straight through. It’s definitely worth checking out.
I loved how the story balanced action and adventure with just enough character moments to make me care. I probably could have handled a little more time getting to know them on a deeper level, but the pace was so snappy and engaging that I stayed hooked the entire time. The audiobook is only about seven hours and it is perfect for a marathon day of getting things done. I listened while prepping Thanksgiving dinner and there were moments where I actually had to stop and focus on my recipe so I didn’t mess anything up for my family.
I’m giving this four stars for the adventure, the fun, and the totally unique premise that kept me listening straight through. It’s definitely worth checking out.
November 24, 2025
Holy cow, this was an action-packed read! I really enjoyed the audio; the narrators all did a fantastic job. It starts fast and holds the pace the whole way through. Most sci-fi is over my head with the technical terms, so I can get lost easily, but this was not that way at all, and I quite enjoyed it. I won’t go into details, but circumstances have happened creating a phenomenon, and a federal agent and a past-life therapist must work together with one of her patients to solve a murder within a limited period of time, crossing multiple states, timelines, etc. You do have to suspend belief, but I had no problem with that here. I was hooked from the start, and it was a one-sitting read. I did not even try to guess how this would wrap up; I just sat back and enjoyed the ride. I loved this all the way through, ending included.
Thank you to Flatiron Books #partner for the gifted copies to review.
Thank you to Flatiron Books #partner for the gifted copies to review.
October 28, 2025
Simultaneous is based on an interesting concept combining genres of time travel fantasy, investigative mystery, and psychological thriller. I like the premise quite a bit, especially the unique take on reincarnation.
The biggest reason I jumped at the chance to read this was Marin Ireland as audiobook narrator. I have never come across a book read by her before that I haven’t adored. Unfortunately her part in this was incredibly small. Ray Porter is a great narrator too, but a very different vibe than I was expecting.
For me this book was engaging but overall just ok. I am sure it will fit the taste of many people. If you love thrillers and FBI procedurals, you should give this a try. If you just love speculative fiction, maybe read a few more reviews see if it still sounds like a good fit.
Thank you to Macmillan Audio for the ALC.
The biggest reason I jumped at the chance to read this was Marin Ireland as audiobook narrator. I have never come across a book read by her before that I haven’t adored. Unfortunately her part in this was incredibly small. Ray Porter is a great narrator too, but a very different vibe than I was expecting.
For me this book was engaging but overall just ok. I am sure it will fit the taste of many people. If you love thrillers and FBI procedurals, you should give this a try. If you just love speculative fiction, maybe read a few more reviews see if it still sounds like a good fit.
Thank you to Macmillan Audio for the ALC.
October 21, 2025
*Thanks to NetGalley and MacMillan audio for early copy for review*
3.5
This has such an interesting premise and while the execution isn't bad I didn't feel any connection to the characters until the very end. There was nothing wrong with the book, but I found myself not caring if our characters lived or died. That being said the very ending did make me wish there was a sequel to this. As a standalone this feels very mid and unsatisfying. If this is the beginning to a series, or will at least have a sequel, then this has potential. There's a lot of set up in explaining the simultaneous lives and a sequel would not have to have that so it could be more action packed. Otherwise it's pretty entertaining, but won't be a long lasting memory.
3.5
This has such an interesting premise and while the execution isn't bad I didn't feel any connection to the characters until the very end. There was nothing wrong with the book, but I found myself not caring if our characters lived or died. That being said the very ending did make me wish there was a sequel to this. As a standalone this feels very mid and unsatisfying. If this is the beginning to a series, or will at least have a sequel, then this has potential. There's a lot of set up in explaining the simultaneous lives and a sequel would not have to have that so it could be more action packed. Otherwise it's pretty entertaining, but won't be a long lasting memory.
August 22, 2025
This is a good semi-sci-fi-mystic book, intriguing on many levels.
I gave it the following SCORE:
Setting: Present day and other times, California, Colorado, and other places
Characters: Grant Lukather, Federal agent from Homeland Security’s Department of Predictive Analytics, Sarah Newcomb, therapist, Marigold, Sarah’s patient, detective Brian Hartley,, and an excellent cast of supporting roles
Overview: Under Sarah’s hypnosis, Marigold believes she can “regress” into another person’s life, including incidents in that person’s past but Marigold’s future. Grant is trying to track down what he believes to be a serial killer who leaves ashes on the forehead of victims. How Sarah, Marigold, and Grant’s paths cross and team up to unravel the complex timelines and convince authorities of the reality of their findings makes this a terrific story.
Recommendation: I rate this book 4 stars
Extras: Fine book that holds your attention to keep up with the cast of characters and changing time frames. The concept of “shared souls” in the universe opens up an entirely different realm of storytelling. Definitely worthy of a sequel or two.
Thanx to NetGalley and Flatiron Books for the opportunity to provide this candid review.
I gave it the following SCORE:
Setting: Present day and other times, California, Colorado, and other places
Characters: Grant Lukather, Federal agent from Homeland Security’s Department of Predictive Analytics, Sarah Newcomb, therapist, Marigold, Sarah’s patient, detective Brian Hartley,, and an excellent cast of supporting roles
Overview: Under Sarah’s hypnosis, Marigold believes she can “regress” into another person’s life, including incidents in that person’s past but Marigold’s future. Grant is trying to track down what he believes to be a serial killer who leaves ashes on the forehead of victims. How Sarah, Marigold, and Grant’s paths cross and team up to unravel the complex timelines and convince authorities of the reality of their findings makes this a terrific story.
Recommendation: I rate this book 4 stars
Extras: Fine book that holds your attention to keep up with the cast of characters and changing time frames. The concept of “shared souls” in the universe opens up an entirely different realm of storytelling. Definitely worthy of a sequel or two.
Thanx to NetGalley and Flatiron Books for the opportunity to provide this candid review.
January 11, 2026
actually really interesting time travel shenanigans!! and the reveal of sarah being the same as charlotte… i can say i wasn’t expecting that in the slightest! i should have been though considering how easily sarah and grant got along. oh well!
i wish there was more of this book like right now. i think a sequel will be coming out? i sure hope so!! grant and sarah i need to see more of your silly activities!! and sarah you need to call off your engagement ASAP!!! get away from travis he doesn’t like you enough!!!!
i wish there was more of this book like right now. i think a sequel will be coming out? i sure hope so!! grant and sarah i need to see more of your silly activities!! and sarah you need to call off your engagement ASAP!!! get away from travis he doesn’t like you enough!!!!
This entire review has been hidden because of spoilers.
November 17, 2025
This book cannot be over 😭
It is fantastic and unputdownable ( that’s been a word since 1830)?!? All of my favorite things are mixed into a mind bending thriller: time travel, parallel lives, secrets, women sleuths, handsome detective, therapy involving past lives, and true love. 💖
Thanks to Belletrist once again I’ve discovered a new favorite 😍
It is fantastic and unputdownable ( that’s been a word since 1830)?!? All of my favorite things are mixed into a mind bending thriller: time travel, parallel lives, secrets, women sleuths, handsome detective, therapy involving past lives, and true love. 💖
Thanks to Belletrist once again I’ve discovered a new favorite 😍
November 19, 2025
A short novel with a neat idea (with surprising parallels to the new show Pluribus!), but with a lackluster execution. It almost feels like an adaptation of a screenplay - which makes sense, considering the author is a screenwriter. It’s quick, very dry, action-heavy, but not that memorable in the end.
September 1, 2025
I found this story absolutely fascinating and really enjoyed the premise of time travel. My only wish is that the ending had been a bit more fleshed out—an epilogue would have added some satisfying closure.
Thank you, #Netgalley and #MacmillanAudio, for this ARC
Thank you, #Netgalley and #MacmillanAudio, for this ARC
November 3, 2025
*my reviews are for my personal record*
I received this book through a Goodreads giveaway. Thank you!!
This was a fun, super quick read for me.
The variety of reincarnation proposed in this thriller (sci-fi?) made for an interesting, multi-layered plot
I received this book through a Goodreads giveaway. Thank you!!
This was a fun, super quick read for me.
The variety of reincarnation proposed in this thriller (sci-fi?) made for an interesting, multi-layered plot
September 10, 2025
I really liked it! It is very fast paced and had several great twists.
November 23, 2025
A fun premise executed like a good thriller film. Would 1000-percent be into a sequel (and TV/movie adaptation).
January 15, 2026
4.5⭐️ rounding up.
November 25, 2025
I’m glad this has been optioned for a feature film, but after that ending, if I don’t get a book 2, I’ll hold a tiny grudge against Eric Heisserer. (Though since he’s the screenwriter for Binge’s Dissolution, among other projects, I’m sure it’ll be a minute before any follow up novel, if that’s even in plan.)
HIGHLY RECOMMEND.
HIGHLY RECOMMEND.
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