The Nightwalker, by Sebastian Fitzek, is a masterpiece of a psychological thriller. It is so good that I made the mistake of wanting to read a few chapters before bed, read a third of the book instead, and then was unable to sleep for an hour after that.
Leon Nader wakes in the middle of the night to find his wife crying, beaten, and packing frantically. He has no recollection of beating her, but when she refuses to answer his questions and rushes out of their apartment, he is struck with a terrible fear: what if he’s started sleepwalking again?
When he was a child, his foster parents found him, sleepwalking, holding a knife over his foster brother. Though his sleepwalking was supposedly cured, he is worried that his violent sleeping self has reappeared.
As Leon strives to learn the truth behind his wife’s flight and subsequent disappearance, he buys a head camera to track where he goes when he sleeps. What he discovers is something he never imagined: there are secret tunnels and hallways throughout his apartment complex, and his sleepwalking self apparently knows all about it. The more he looks, the more he wonders: is he more than a wife beater. Is he, perhaps, something even darker?