You don't miss your genes till they turn prehistoric.
To save the world from nuclear holocaust, the Timekeeper must start evolution running backward. And man, is he pissed. So pissed, he's decided to backdate humans right out of existence.
As people morph in and and out of prehistoric animals, a ragtag band led by Galloping Ariadne and Philip the Assault Otter careens through time fighting off dinosaurs and time storms as they try to convince the Timekeeper, now convinced he's cruise director aboard the Titanic, to give humanity one last chance.
But the greatest threat of all comes from a right-wing cabal led by a megalomanic saber-tooth who plans to bypass humanity all together and set himself up as a god.
Specifically, Seth, God of Evil.