Not satisfied with the limits on human endurance, the government’s Defense Advanced Research Projects Agency (DARPA) has created the Excelsior program to break human performance barriers. Dr. Evan Galloway, a brilliant physiologist from MIT, has been tasked with developing nanotech-based red blood cells that produce a 236-fold boost in oxygen efficiency.Though chosen for his superior scientific talent, Evan hasn’t been able to create functioning Nan Airs. Fed up with Evan, DARPA Director Dana Brines opens up the once-classified project into a worldwide scientific competition.

Soon thereafter, billionaire investor, Jack McKnight, announces an impossibly dangerous quintuple Ironman triathlon, The Aletheia, as an opening act to the Olympics—and he’s competing. Dejected and with a personal vendetta against McKnight, Evan enters the race only to discover that his thrill-seeking little brother, Luke, is out of prison and has also entered. Now Evan must not only survive the race against an egomaniacal and likely enhanced opponent, but also save his brother and the Olympics from sure destruction.

Without Limits is an ethically-charged science fiction/action adventure novel in the page-turning vein of Michael Crichton. It explores the moral implications of our natural drive to cheat, the grudges we hold, and our looming ability to enhance our biology through technological means.

“Impressively well written, Without Limits is a compelling action/adventure thriller of a read from beginning to end — and clearly establishes author Dustin Grinnell as an imaginative storyteller of the first order.”- Midwest Book Review

“A well-researched thriller with taut and gripping tension. The story flows smoothly with many threads, keeping the reader guessing through to a brilliant and innovative climax. An eye-opener in every way, a five-star rating.” – Deepak Menon, Readers’ Favorite

“A tense, complicated tale about characters with competing agendas. A great read with a story that keeps moving, and characters you can care about.” – Lis Carey’s Library

“An interesting choice of subject matter so that the effort to “revolutionize endurance sports” becomes fodder for a techno-thriller, which starts with a unique idea and works through some interesting narrative surprises.” – Judge, 23rd Annual Writer’s Digest Self-Published Book Awards

Purchase Without Limits on Amazon as an e-book for $0.99, or as a paperback for $9.95. See picture from the 2015 Tri-Mania Summit in Cambridge.