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Millie and Mabel's Afterlife Adventure
Set in a vibrant American city, this paranormal cozy mystery blends FBI crime scenes, heavenly hijinks, and spectral sleuthing in a race that stretches from the mortal world to the gates of Heaven.
Death was not supposed to derail their fun.
Mabel and Millie have been causing havoc together for decades, and they are not about to let a little thing like death stop them. Bored with Heaven’s endless perfection, these two lifelong troublemakers hatch a plan to sneak back to Earth for some good old-fashioned haunting. But their spectral shenanigans take an unexpected turn when they stumble straight into an FBI investigation for a vicious serial killer.
Enter Sarah Sadler, a brilliant but struggling FBI agent who can see and hear them thanks to a recent near-death experience that almost wrecked her career. As the body count rises, Millie and Mabel realise that solving crimes is far more interesting than causing trouble, especially when they have unique ghostly talents to help Agent Sadler crack the case.
With time running out and lives on the line, this unlikely trio must learn to work together across the boundaries of life and death to catch a murderer before they strike again.
Perfect for fans of Mary Janice Davidson’s Undead series and the sharp humour of Janet Evanovich’s Stephanie Plum series, this afterlife mystery blends laugh-out-loud mischief, female friendship, and fast-paced serial killer suspense with a supernatural twist.
Death was not supposed to derail their fun.
Mabel and Millie have been causing havoc together for decades, and they are not about to let a little thing like death stop them. Bored with Heaven’s endless perfection, these two lifelong troublemakers hatch a plan to sneak back to Earth for some good old-fashioned haunting. But their spectral shenanigans take an unexpected turn when they stumble straight into an FBI investigation for a vicious serial killer.
Enter Sarah Sadler, a brilliant but struggling FBI agent who can see and hear them thanks to a recent near-death experience that almost wrecked her career. As the body count rises, Millie and Mabel realise that solving crimes is far more interesting than causing trouble, especially when they have unique ghostly talents to help Agent Sadler crack the case.
With time running out and lives on the line, this unlikely trio must learn to work together across the boundaries of life and death to catch a murderer before they strike again.
Perfect for fans of Mary Janice Davidson’s Undead series and the sharp humour of Janet Evanovich’s Stephanie Plum series, this afterlife mystery blends laugh-out-loud mischief, female friendship, and fast-paced serial killer suspense with a supernatural twist.
322 pages, Kindle Edition
Published April 29, 2026
About the author
Katherine Hastings
26 books275 followersUSA Today bestselling author Katherine Hastings writes books that make readers laugh, swoon, and escape into unforgettable adventures. From hilarious women’s fiction to swoon-worthy romance and high-stakes suspense, she weaves stories filled with heart, humor, and a dash of chaos.
Her books have been AUDIE Award-nominated for Best Humor and have won the SOVAS Award for Best Humor, proving that laughter and storytelling go hand in hand.
When she’s not crafting page-turning tales, you’ll find her in Wisconsin, snuggling her husband, two Boston Terriers, and the world’s naughtiest cat. If she’s not writing indoors, she’s outside with her horses, ducks, and Sebastopol geese—because life is better with a little fur and feathers.
Her happy place? Floating in the lake with a book, a cold drink, and a plate of Fried Wisconsin Cheese Curds.
Her books have been AUDIE Award-nominated for Best Humor and have won the SOVAS Award for Best Humor, proving that laughter and storytelling go hand in hand.
When she’s not crafting page-turning tales, you’ll find her in Wisconsin, snuggling her husband, two Boston Terriers, and the world’s naughtiest cat. If she’s not writing indoors, she’s outside with her horses, ducks, and Sebastopol geese—because life is better with a little fur and feathers.
Her happy place? Floating in the lake with a book, a cold drink, and a plate of Fried Wisconsin Cheese Curds.
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Displaying 1 - 17 of 17 reviews
May 3, 2026
Oh wow! This was so much fun that I just loved. The whole plot idea caught my imagination and the author didn't disappoint.
I have ready lots of mysteries and cozy's in particular that feature the super natural witches, vampires, shifters but this was so unusual to star ghosts and so much fun that I have to wonder why it hasn't become the norm. The author has come up with a hit with this series and a certainly hope it becomes a long running series. It was a hoot reading about Mabel and Millie, two ghosts who are board with heaven and find a way to return to earth to cause chaos and mayhem, instead they end up stopping a serial killer. There interaction with Sarah an FBI agent were so amusing, especially in the beginning when she struggled to believe her own eyes. The mystery was good and well worked, the different ways the ghosts got involved in the case from following suspects, to looking at evidence was another interesting aspect to the case.
When two best friends die and find themselves together in heaven the last think they expect was to get board, especially as they never really expected to end up there. So when they discover a way to return to earth, they jump at the opportunity to return cause some mischief, especially to the people who costume wrong in life. The only problem is they returned to do a job, help the newly dead move on but when there first case involves the ghost of a murdered woman, they begin to wonder if they can do more then just help. When they discover another murder victim, Mabel and Millie seek out the only one that might be able to help them stop a serial killer. FBI agent Sarah is a new recruit with something to prove but begin head strong caused an accident that could not only see her being kicked out of the FBI but also seeing ghost. Can the three of them work together to solve the case, especially as the rest of the FBI are totally looking in the wrong direction?
Will be definitely adding this series and the author to my must read list, so I don't miss the next book.
I was given this free review copy book at my request and have voluntarily left this review.
I have ready lots of mysteries and cozy's in particular that feature the super natural witches, vampires, shifters but this was so unusual to star ghosts and so much fun that I have to wonder why it hasn't become the norm. The author has come up with a hit with this series and a certainly hope it becomes a long running series. It was a hoot reading about Mabel and Millie, two ghosts who are board with heaven and find a way to return to earth to cause chaos and mayhem, instead they end up stopping a serial killer. There interaction with Sarah an FBI agent were so amusing, especially in the beginning when she struggled to believe her own eyes. The mystery was good and well worked, the different ways the ghosts got involved in the case from following suspects, to looking at evidence was another interesting aspect to the case.
When two best friends die and find themselves together in heaven the last think they expect was to get board, especially as they never really expected to end up there. So when they discover a way to return to earth, they jump at the opportunity to return cause some mischief, especially to the people who costume wrong in life. The only problem is they returned to do a job, help the newly dead move on but when there first case involves the ghost of a murdered woman, they begin to wonder if they can do more then just help. When they discover another murder victim, Mabel and Millie seek out the only one that might be able to help them stop a serial killer. FBI agent Sarah is a new recruit with something to prove but begin head strong caused an accident that could not only see her being kicked out of the FBI but also seeing ghost. Can the three of them work together to solve the case, especially as the rest of the FBI are totally looking in the wrong direction?
Will be definitely adding this series and the author to my must read list, so I don't miss the next book.
I was given this free review copy book at my request and have voluntarily left this review.
Review of advance copy received from Author
If you had to guess, where would you guess THE doorway to heaven would be located on earth? Whatever you guessed, I'm leaning toward you being wrong. And, nope, not telling. You'll have to read this humorous, quite quirky tale of two heavenly souls who come down to earth to...well, do a job. It is telling that they have hopes of doing a few other fun things, too, while here, but that's half the fun. I got this book late and wanted to have a review ready and up for publication day, so didn't really take notes, but after a somewhat slow start, the pace begins to pick up with their return to earth. Let's just say, things didn't go as planned.
I'm not going to detail the plot much but will say that Millie and Mabel were friends for about 90 years before they went to heaven. Even they aren't quite sure how they got there, to be honest, so that adds to the sense of anxiety that poor Millie feels at Mabel's idea. Let's just say, if you think you know what a Crossing Guard is, you're right but wrong. As noted, the start was a bit slow, setting the stage as the duo admit that they are finding perfection in heaven wonderful but a bit boring. Don't ask. Read the book. Grin.
The story eventually evolves with them being visible to FBI agent Sarah Sadler who had had a near death experience. Sarah is investigating a serial killer and the dynamic duo find themselves getting involved. Does it go smoothly? Well, no, but that's half the fun. They're also doing their initial job, not to mention a bit more, so their stay on earth is eventful. I think you'll find it intriguing and amusing. Millie and the always more adventurous Mabel are winging it most of the time but discover they're not half bad at this investigating thing. My thanks to author #KatherineHastings and to #ReaganDavis for introducing me to this fun pair of Spectral Sleuths in her newsletter.
I'm not going to detail the plot much but will say that Millie and Mabel were friends for about 90 years before they went to heaven. Even they aren't quite sure how they got there, to be honest, so that adds to the sense of anxiety that poor Millie feels at Mabel's idea. Let's just say, if you think you know what a Crossing Guard is, you're right but wrong. As noted, the start was a bit slow, setting the stage as the duo admit that they are finding perfection in heaven wonderful but a bit boring. Don't ask. Read the book. Grin.
The story eventually evolves with them being visible to FBI agent Sarah Sadler who had had a near death experience. Sarah is investigating a serial killer and the dynamic duo find themselves getting involved. Does it go smoothly? Well, no, but that's half the fun. They're also doing their initial job, not to mention a bit more, so their stay on earth is eventful. I think you'll find it intriguing and amusing. Millie and the always more adventurous Mabel are winging it most of the time but discover they're not half bad at this investigating thing. My thanks to author #KatherineHastings and to #ReaganDavis for introducing me to this fun pair of Spectral Sleuths in her newsletter.
April 30, 2026
Millie and Mable have been friends since they were 3. They've had each other's back through thick and thin and now, 90 years later, they're living together in Heaven, having died a couple hours apart. And yes, Heaven is perfect, you can have everything you wish for with a snap of your fingers… and they're bored to death. So they apply to go back on Earth as Crossing Guards, to help the newly dead cross over.
Soon, what started as a half-cocked plot to get revenge of petty grievancies becomes a serious mission to save lives when two of the souls they help cross over were victims of a serial killer. The two elderly ladies even team up with an FBI Agent who can see them to solve the murders.
This is an original idea. Our amateur sleuth aren't only elderly ladies, they're ghosts from Heaven!
Maybe the story starts off a bit slow, and the cozy mystery part only gets going 30% into the book, but the plot is just the richer for the time spent setting up the protagonists back story.
Millie and Mabel are described in depths, Millie is a bit of a whiner and a worrier, while Mable is a gung-ho spitfire, always ready to cause mayham. FBI Agent Sarah Sadler is a lonely overachiever, brought low by a mistake.
With a bit more tweaking this would have been a perfect story. But even with a few imperfections, it's a wonderful read and I look forward to the Spectral Sleuths next adventure.
I received an advance review copy for free, and I am leaving this review voluntarily.
Soon, what started as a half-cocked plot to get revenge of petty grievancies becomes a serious mission to save lives when two of the souls they help cross over were victims of a serial killer. The two elderly ladies even team up with an FBI Agent who can see them to solve the murders.
This is an original idea. Our amateur sleuth aren't only elderly ladies, they're ghosts from Heaven!
Maybe the story starts off a bit slow, and the cozy mystery part only gets going 30% into the book, but the plot is just the richer for the time spent setting up the protagonists back story.
Millie and Mabel are described in depths, Millie is a bit of a whiner and a worrier, while Mable is a gung-ho spitfire, always ready to cause mayham. FBI Agent Sarah Sadler is a lonely overachiever, brought low by a mistake.
With a bit more tweaking this would have been a perfect story. But even with a few imperfections, it's a wonderful read and I look forward to the Spectral Sleuths next adventure.
I received an advance review copy for free, and I am leaving this review voluntarily.
April 29, 2026
I think the best way to describe this one is a paranormal cozy mystery… with a whole lot of laughs.
Millie and Mabel are living their best afterlife—complete with unlimited perks (cake on demand, anyone? 🎂). But perfection gets a little… boring. In life, they were known for being just a bit mischievous—standing up for others and pulling the occasional well-deserved prank.
So naturally, they decide to apply to become “crossing guards”—helping newly departed souls transition to heaven… with a side mission of haunting a few select people back on Earth.
But things take a turn when they stumble upon victims of a serial killer, and suddenly their mission shifts to solving the murders.
This story is such a fun mix of:
👻 humor
🔍 mystery
🤯 twists and turns
💛 lovable, memorable characters
I especially loved Sarah, a struggling FBI agent trying to make her own way while living in the shadow of her father—she added a great layer to the story!
It’s a page-turner that balances lighthearted fun with real intrigue, and I’m already excited to see what’s next for Millie and Mabel!
I voluntarily read and reviewed an advanced copy of this book. All thoughts and opinions are my own.
Millie and Mabel are living their best afterlife—complete with unlimited perks (cake on demand, anyone? 🎂). But perfection gets a little… boring. In life, they were known for being just a bit mischievous—standing up for others and pulling the occasional well-deserved prank.
So naturally, they decide to apply to become “crossing guards”—helping newly departed souls transition to heaven… with a side mission of haunting a few select people back on Earth.
But things take a turn when they stumble upon victims of a serial killer, and suddenly their mission shifts to solving the murders.
This story is such a fun mix of:
👻 humor
🔍 mystery
🤯 twists and turns
💛 lovable, memorable characters
I especially loved Sarah, a struggling FBI agent trying to make her own way while living in the shadow of her father—she added a great layer to the story!
It’s a page-turner that balances lighthearted fun with real intrigue, and I’m already excited to see what’s next for Millie and Mabel!
I voluntarily read and reviewed an advanced copy of this book. All thoughts and opinions are my own.
May 21, 2026
A 4.5 stars for Katherine Hastings' Millie and Mabel's Afterlife Adventures, a very fun paranormal cozy mystery. I will admit that I enjoy stories with ghosts, so I knew I had to read this book. What made it such a fun (and funny read) was that the characters are two best friends who died in their 90s and went to Heaven (a perfect place), but were bored and offered a chance to return to Earth (a not-so-perfect place).
Before I go further, I would like to thank Book Sirens, and the author, Katherine Hastings, for providing this advance review copy (ARC) for free, and I am leaving this review voluntarily.
The story is told from both Mille's and Mabel's point of view, with each chapter switching between the two amateur, spectral sleuths. At first, it was a little hard to tell the difference, but as the story progresses, it becomes easier, as the characters developed. The same is true with FBI Agent Sarah Sadler, who is the only one who can see/hear Millie and Mabel. Together, the trio manage to solve, through slightly unconventional means, several murders of young women.
One draw back that I found was that some of the writing felt a bit repetitive, but overall, it didn't take that much away from the story. Despite that, I highly recommend Millie and Mabel's Afterlife Adventures for anyone who enjoys cozy mysteries, and ghosts. I definitely want to continue reading this series.
Before I go further, I would like to thank Book Sirens, and the author, Katherine Hastings, for providing this advance review copy (ARC) for free, and I am leaving this review voluntarily.
The story is told from both Mille's and Mabel's point of view, with each chapter switching between the two amateur, spectral sleuths. At first, it was a little hard to tell the difference, but as the story progresses, it becomes easier, as the characters developed. The same is true with FBI Agent Sarah Sadler, who is the only one who can see/hear Millie and Mabel. Together, the trio manage to solve, through slightly unconventional means, several murders of young women.
One draw back that I found was that some of the writing felt a bit repetitive, but overall, it didn't take that much away from the story. Despite that, I highly recommend Millie and Mabel's Afterlife Adventures for anyone who enjoys cozy mysteries, and ghosts. I definitely want to continue reading this series.
Read
April 28, 2026This one was a nice surprise. The premise alone sold me: two elderly best friends, thoroughly done with the peace and quiet of Heaven, who head back to Earth for some fun and end up tangled in a murder case alongside an FBI agent who can see ghosts. Cozy mystery perfection.
For the most part, it delivers. Millie and Mabel are sweet and genuinely funny, the found family element is everything, and the book is filled with interesting women — living and dead alike.
The dual POV took a little getting used to, as their voices feel similar at first, but they do become their own people as the story settles. My only real complaint is the pacing: the mystery doesn't fully kick in until around the 25% mark, which makes the opening feel a little unsteady.
⭐⭐⭐⭐ (3.7/5)
I received an advance review copy for free, and I am leaving this review voluntarily.
For more reviews like this, find me at @oddpagesonly on Substack and Instagram. ✨
For the most part, it delivers. Millie and Mabel are sweet and genuinely funny, the found family element is everything, and the book is filled with interesting women — living and dead alike.
The dual POV took a little getting used to, as their voices feel similar at first, but they do become their own people as the story settles. My only real complaint is the pacing: the mystery doesn't fully kick in until around the 25% mark, which makes the opening feel a little unsteady.
⭐⭐⭐⭐ (3.7/5)
I received an advance review copy for free, and I am leaving this review voluntarily.
For more reviews like this, find me at @oddpagesonly on Substack and Instagram. ✨
May 7, 2026
I received an advance review copy for free, and I am leaving this review voluntarily.
This was such a joyful, uplifting and humorous story. I absolutely adored the two main characters, they are so sweet and mischievous and their bond is illustrated in such a heart felt way, you can really feel it.
The contrast of the really quite brutal murders with the cosy mystery elements really gives the book depth and intrigue.
This book had me going through a complete range of emotions, from laughing at Millie and Mables antics, to welling up with the emotion of some scenes! I didnt expect so much from such a short book.
I normally really struggle to get into "cosy" genre books, but I thought id take a chance on this one, and im really glad that I did. It caught my attention from the start, it never felt cheesy or immature. Just a really refreshing and enjoyable story. Id definitely pick up the next book in the series.
This was such a joyful, uplifting and humorous story. I absolutely adored the two main characters, they are so sweet and mischievous and their bond is illustrated in such a heart felt way, you can really feel it.
The contrast of the really quite brutal murders with the cosy mystery elements really gives the book depth and intrigue.
This book had me going through a complete range of emotions, from laughing at Millie and Mables antics, to welling up with the emotion of some scenes! I didnt expect so much from such a short book.
I normally really struggle to get into "cosy" genre books, but I thought id take a chance on this one, and im really glad that I did. It caught my attention from the start, it never felt cheesy or immature. Just a really refreshing and enjoyable story. Id definitely pick up the next book in the series.
Review of advance copy received from Author
I absolutely adored this book! A paranormal mystery that made me LOL! I’m a big fan of The Wilder Widows series, and when I was given an opportunity to do an ARC for this new series, I jumped on it. I’m so glad I did! It had all the hilarious humor and heart of The Wilder Widows that I love but with a paranormal mystery mixed in! Millie and Mabel are a hoot and I loved watching them transform from troublemaking ghosts into sleuths helping Agent Sadler hunt down the killer. The character development and relationships were just as fun as the mystery itself, and I thought it gave the book so much more depth than just a case to solve. If you’re looking for a really fun new twist on the cozy mystery genre that will make you laugh out loud, this is a great book to try! Hoping for lots more adventures with my favorite new spectral sleuths!
May 1, 2026
I am an ARC reader for Book Sirens and this is my honest opinion. This book is a lot of fun - apart from the grisly crime of course! Mabel and Millie have been friends for 90 years - since they met at the age of 3. A pair of compulsive mischief and Mayhem makers, their victims were only ever those who deserved it - bullies, nasty people etc. So they end up dying, one very soon after the other and find themselves in heaven. Perfect, tranquil, happy all the time - and boring! Given the chance to go back to earth they plan on doing some haunting and a lot of the aforementioned M & M. Things get a lot more exciting than they expected however. I really enjoyed reading about these two naughty old ladies' adventures. I would love to read more of them. This was a great fun read!
April 24, 2026
This book was a little bit of a rough read for me. I did like the characters Millie, Mabel and Sarah. I also liked the character growth she gave the characters.
FYI, I received an advance review copy for free, and I am leaving this review voluntarily.
The beginning is pretty slow. You don’t encounter the mystery until you’re about one-third into the book. There’s a lot of world building and setup, almost too much. Even when I got into the mystery, at times I felt like there was too much repetitive dialogue.
I love the concept of this book and the core of it is good, I just overall felt like it had a lot of baggage surrounding it.
FYI, I received an advance review copy for free, and I am leaving this review voluntarily.
The beginning is pretty slow. You don’t encounter the mystery until you’re about one-third into the book. There’s a lot of world building and setup, almost too much. Even when I got into the mystery, at times I felt like there was too much repetitive dialogue.
I love the concept of this book and the core of it is good, I just overall felt like it had a lot of baggage surrounding it.
May 17, 2026
Millie and Mabel were fast friends all their lives and nothing has changed when they went to heaven. All is wonderful there but a little boring for the mischievous friends. When they get a chance to go back to earth to help lost souls to find their way to the afterlife they have all the good intentions and some hidden agendas . After meeting an FBI agent, who can see and communicate with ghosts after a near death experience, Millie and Mabel decide to help Sarah to find the murderer. Only they can get insideer information from the dead and a complicated case can be solved and a serial killer brought to justice.
May 12, 2026
This was a fun read. Millie and Mabel, best friends since childhood, are bored in Heaven. They get assigned to go back to earth as "crossing guards". Their earthly adventures were entertaining as they learned how to use their energy. I did think the book could have been shortened as it was repetitive in several sections. I would read the next in the series as I like the story idea.
I received a free copy of this book from the author and am voluntarily leaving an honest review.
I received a free copy of this book from the author and am voluntarily leaving an honest review.
May 17, 2026
Thanks to BookSirens for the ARC.
This book was charming, quirky, and a lot of fun. The premise of besties in heaven being in their seventies because it represented the most joy-filled time of their lives was so sweet!
I really liked the way the ghostly abilities were useful on earth, and indeed the adventure that they got into was a lot of fun too.
Some of the writing felt a bit repetitive, but overall, it was a good cosy read.
This book was charming, quirky, and a lot of fun. The premise of besties in heaven being in their seventies because it represented the most joy-filled time of their lives was so sweet!
I really liked the way the ghostly abilities were useful on earth, and indeed the adventure that they got into was a lot of fun too.
Some of the writing felt a bit repetitive, but overall, it was a good cosy read.
May 21, 2026
Loved this book. I enjoyed reading about Millie and Mabel and their desire to continue having adventures once they got to heaven. I hope the writer continues writing about their adventures on earth, helping people as well as making innocent mischief.
Review of advance copy received from Author
This started out kind of slow and iffy and then it moved into something really good so stay with it. It's a really good murder mystery.
May 2, 2026
An enjoyable read.
May 21, 2026
Fun, a great pace, and great characters.
If you want a fun, creative read, with a good storyline, this is it. Looking forward to the next adventure.
If you want a fun, creative read, with a good storyline, this is it. Looking forward to the next adventure.
Displaying 1 - 17 of 17 reviews