Doormat Wesley Gibson discovers that his recently murdered father – who Wesley never knew – belonged to a secret guild of assassins. After a leather-clad sexpot drafts Wesley into the society, he hones his innate killing skills and turns avenger.
The protagonist is diagnosed with a lot of mental health disorders that prove to be not quite accurate, though that's more an issue of the people around him not knowing how to properly understand the situation than anyone attempting to invalidate his own sanity. There's also a lot of (unrelated) manipulation and deception going on in the story.