Dead Vault — Daniel Eness

Arclight's in trouble. Out of work and out of time, he's losing his own mind in search of someone else's. That's the good news. It seems that dementia isn't the only thing in North Tree that is in the business of swallowing hearts. When Arc goes down, he goes down hard. Make it to the end, and realize why the question really isn't: Will Arc Adams survive the dead vault? ...but, will he want to?