RIFT: The Sixth Extinction

by Thomas Asher, Frederic Wierum (Contributor), Mark Witton (Consultant Editor)

Northern Africa, 2053: a groundbreaking paleontological discovery sparks hope for restoring the world’s collapsing bird populations as a “de-extinction” renaissance unfolds. Nearly a century later, deep under the Sahara, physicists explore the universe’s mysteries while massive surface domes test self-sustaining ecosystems filled with revived, genetically resurrected species. As these timelines converge, humanity finds itself entangled in a brutal creation of its own making. One that unleashes ancient lifeforms, once lost to extinction, into a denuded world. A hidden reality is unmasked—revealed by the RIFT—and it does not bend to us.

724 pages, Paperback

Published October 31, 2025

About the author

Thomas Asher uses writing as a medium to explore big questions. Through his work, he takes a deep dive into the depths of scientific understanding to develop compelling, character-driven stories. As a former researcher in the fields of neuroscience and biochemistry, Tom's passion for science has a profound impact on his cautionary tales for humanity's future.

Reviews

[Bill · Rating 5 out of 5]

RIFT is a sci-fi action thriller to its core, and one that's been missing from the bookshelves of fans of the genre for a long time. A true page-turner, Thomas Asher hits a home run with this story. The book is, in some ways, a spiritual successor to Crichton's Jurassic Park. In reality, it is so much more; it explores topics that are perhaps more relevant than ever, and marries documentary quality depictions of prehistory with science and horror that sometimes feel all-too-real.

As a dinosaur lover and palaeontolgy enthusiast I was giddy with excitement while reading this book; I turned page after page in a furious ecstasy, as I ultimately devoured the ~700 page book in just three days. The book is meticulously researched, in a way that almost made me weep tears of joy when I realized how diligent the author was in depicting not just the prehistoric fauna, but also applications of technologies we may well see in the near future. The way Asher combined all his different ideas into one cohesive package is truly impressive.

But who is it for? Obviously it's geared primarily towards the science fiction crowd, but whatever you might want from a story like this, RIFT has it all: quasi-military future dystopia, horror (both cosmic and conventional), genetics, physics and more. The glossary and bestiary sections at the end will help even unfamiliar readers get familiar with the science. Realistic characters with complex backstories combined with careful world-building create the impression of a world that isn't just the product of an imaginative, futurist mind, but one that really is coming; and in some ways is already here. All wrapped in a tight, hard-hitting narrative that gets your blood pumping and your skin crawling as your hands keep turning the page.

I digress, though. I could about this book for hours, but spoiling even an inkling of this story would be doing it a disservice. To conclude, Asher has managed to pen one of the most impressive books I've read in recent years. His exploration of humanity, ethics, trauma and science all come together in the form of RIFT: The Sixth Extinction. A great book, in every sense of the word; I would (and will) recommend it to anyone.

Thank you, Thomas. I'm really hoping for a sequel.

[Thomas Strimpel · Rating 5 out of 5]

RIFT: The Sixth Extinction is a dark, fascinating story that will equally terrify and intrigue with suspenseful moments of horror and convincing worldbuilding. I found so many scenes to be gripping, disturbing and memorable, and the Introduction will not disappoint the readers who came for a cerebral sci-fi/horror story featuring a variety of prehistoric animals. The scenes they are present for are reminiscent of the animals featured in Jurassic Park: always with realistic anatomy and behavior in mind, with well-paced, memorable sequences that never overstay their welcome.

This story’s text also features intriguing, complex characters with distinct voices, set amidst a grounded yet grim futuristic setting that left me turning page after page. The author’s fascination with such scientific subjects as paleontology, genetics and quantum physics is infectious, and really helps to make the world depicted here as realistic and visceral as possible. These areas of research are presented with little jargon and are quite easy to follow with Asher’s writing.

RIFT is a fantastic read and I cannot recommend it enough.

[Danny Donahue · Rating 5 out of 5]

I was lucky enough to get a chance to read this book early. Rift is a tremendous work of science fiction/horror and an instant classic for lovers of dinosaur fiction. It's a harrowing, grounded vision of both a possible future and our prehistoric past. The world of the novel feels immense, and it's filled with futuristic technology, detailed science both real and speculative, and human characters thrown into direct contact with what may be the most haunting depictions of dinosaurs I've read to date. It's meticulously researched and wonderfully written. For me, the language and style of a novel is incredibly important, and Asher's use of words on the page is fully immersive, graceful, technical but not overwhelming. I hoped that the book would be unafraid to go fully into the dark recesses of where a sci-fi novel featuring dinosaurs could go, and it did not disappoint. The narrative is told from various character perspectives and the characters feel distinct and believable and multidimensional. I'm a massive fan of dinosaurs, and Rift would easily scratch that itch for any with similar interests, but I'd also emphatically recommend it to the sci-fi community at large. Highly recommend.

[Pedro Salas · Rating 4 out of 5]

Rift is poetry and raw meat simultaneously. Its pages seamlessly lay out a chain of effects, directly resulting from the characters' actions, that mirror the principles found in Newtonian and Quantum physics.
Despite the fact that these outcomes are governed by laws that perhaps not even the protagonists can fully comprehend, their harrowing repercussions are as inevitable as nature doing what it does best: simply being nature. Thomas Asher haunts his story with a list of ceremonial breakdowns, in the shape of biological forms as much as the characters’ expectations, which are narrated with exquisite attention to their inner and outer details. And by doing this, he includes us in one of the greatest science fiction horror stories of our time.

[Mariano Canales · Rating 5 out of 5]

A true hard science fiction thriller with dinosaurs, it will keep the reader on the edge of their seats with exciting scenes from a fascinating, terrifying, and almost real world.
RIFT is greatly differentiated from other works of its genre by its content: cosmic and existential horror, military fiction, climate change... and dinosaurs. All of this coexists in a great story full of vivid characters, marked by loss and pain, who will have to face situations more dangerous than the fears that overwhelm their fragile minds.

[Ron Day · Rating 5 out of 5]

Rift: The Sixth Extinction hooked me from page one.

Thomas Asher does an amazing job balancing the science with real emotion and tension. The characters feel human, the world building is detailed without ever dragging, and the suspense builds perfectly. By the end, I couldn’t stop thinking about the message behind it all…how easily good intentions can spiral out of control.

If you like Jurassic Park, Interstellar, or anything that makes you question our future, this book is a must-read. It’s smart, thrilling, and unforgettable.

[Nicholi · Rating 5 out of 5]

The Rift is the book I’ve been waiting for. As a fan of master storytellers like Michael Crichton and Andy Weir, I was thrilled to find that Thomas Asher has achieved a perfect balance between meticulously researched science and an imaginative world that feels eerily close to our own. His prose is immersive, his attention to detail remarkable, and his storytelling both intelligent and gripping. Beautifully crafted from start to finish, The Rift is sure to become a new favorite for fans of science fiction and thrillers alike.

[Reader · Rating 4 out of 5]

An amazing first dive into Sci-Fi by author Thomas Asher

RIFT is in every way emblematic in what you want from great Science Fiction, Horror and Creature Feature storytelling. Blending a mix of the best Crichton-esque storytelling with fascinating near-future world building that commentates on our own in ways that feel natural. A must read for those interested in paleontology, Sci-Fi, and great fun thrillers with a hint of cosmic horror. Read it!

[Karen Nadeau · Rating 5 out of 5]

I’m a big horror fan and this story delivers! There are passages that are truly terrifying similar to some of HP Lovecrafts tales. This book had me turning the page and anxious to know what comes next. The sci fi elements are detailed and well done. The characters in the story are really well developed and each one has a unique place within the story. This is a well crafted tale that kept my attention. I highly recommend this one!

[Mike Nadeau · Rating 5 out of 5]

Author has captured what could likely happen in the near future. The story is a well crafted and believable piece of hard sci fi. Characters are realistically complex and the story is compelling. Illustrations, appendix and bestiary are an added bonus to an already excellent cautionary tale. I have read a lot of hard sci fi, this one is in the top 5.

[MK Mons · Rating 5 out of 5]

This book is a must-read for all lovers of prehistoric creatures, suspense and science thrillers. Asher combines the technical grit of Crichton with the visceral dread of Vandermeer in this stunner of a novel. Solid research makes this book feel real, but the characters, human and creature alike, bring it to life.