Exponent

Extant #2

by Jack Croxall

Suspense is a killer. But what about everybody else?

Dr. Ina Adama has big problems. Another time traveller is demanding that she help him kill every last living dinosaur or risk dooming humanity to non-existence. But can he be trusted? And is there someone else on the planet with an agenda all of their own?

Exponent is a sci-fi suspense novella and is the second book of the Extant series.

93 pages, Kindle Edition

Published March 9, 2026

About the author

Trained as a scientist, Jack Croxall concluded a life in the lab wasn't for him. After discovering a passion for words and stories he's now a writer!

Reviews

[Nisha]

This was an exciting follow-up to the dino time-travel novella, Extant! I enjoyed the ecology, the action, and the suspense. But that cliffhanger! Come on! At least I now know the sequence will be a pick your own adventure, and we will finally get a satisfying ending (or hopefully many of them)!

[B. Philippe]

Another wonderfully-told tale from Jack Croxall. Exponent is fascinating, playful and full of suspense. I especially enjoyed the riddles and the Sagan Monstrosity Cards card game. Packed with great ideas!

“You don't like my jokes? I'm literally the funniest man on this planet!”

A great read.

[Johnie C]

very good read

I enjoyed reading this book and I recommend this book to anyone who likes to read time and space travel books with twists that causes you to think.

[elise]

I’m left with so many questions for the next one but I really liked this. Timelines are kind of mixing as well as characters interlinking which is cool.