Micajah Fenton is eighty and about to end his life when he finds a crater in his front yard, a wrecked time glider at the bottom of it, and a virtual woman standing on his lawn.
She sends him back into his ten-year-old body carrying everything he knew at eighty.
What I liked is that none of it works as a cheat code. Every change Cager makes bends the future he remembers out of shape, until the one mistake he most wants to fix sits further away than when he started. There is comedy in it, and a detour through the Cretaceous, but the spine of the book is consequences.
Come for the premise. Stay for how little knowing the future turns out to be worth.