Dead Vault by Daniel Eness
Approx. 50,120 words.
Published on June 9, 2013.
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.