Drop Dead, My Lovely — Ellis Weiner

A one-time mild-mannered bookstore clerk transformed into a hard-boiled private detective thanks to a head injury, Pete Ingalls decides to open up his own detective agency, taking Raymond Chandler as his model, and finds himself on the trail of a variety of shady characters, dealing with damsels in distress, and tracking a killer, with only his delusion to sustain him. Reprint.