Hit Me by Lawrence Block

 

This isn't so much a novel as it is a series of various-length short stories, plausibly told in order. That's fine, but it does mean there's less of an overarching thing happening--though the first and last stories do both involve the main character being called out of retirement. It's Block, one of the most casually witty authors I've read, so it's immensely readable and often laugh-out-loud funny. Block does like to have his characters know all kinds of weird stuff, which makes sense, because people do know all kinds of weird stuff.