Another sharp little novella from Tor.com, most of the book focuses on the premise that some people die before their time, those people become ghosts, and those ghosts can take years off a human's age, add it to their own, and cross over when they reach the age they were destined to die. But this exchange can go both ways, and ghosts can be trapped and forced to take years against their will. It's a pretty cool idea, but I would have liked more.