I Bought an Island Before Doomsday

Billionaire Ethan Crow is betrayed by his own brother, but when he opens his eyes, he finds himself eleven months before the end of the world, still carrying every memory of what was taken from him. Armed with that knowledge and a deadline that is closing in, he sets out to reclaim his fortune and settle the score. The source ends mid-thought, so the story here is limited to his betrayal and his determination to return and get even.