Outer Darkness — James Axler

FIRE AND ASHES

His new world born out of the fire and ashes of a nuclear exchange, a rogue warrior searches for ways to undo the past. With brother-in-arms Grant and the archivist Brigid Baptiste, he dares to seek out the secrets of time....

Kane and his fellow exiles are thrown into a reality where the nukecaust didn't happen--instead, the inhabitants had driven the enemy from the planet. But now the dark forces are back for a final confrontation in a war that may bring ultimate freedom or final destruction.