Smoke

Due to a foiled burglary in a high-tech lab doing research for cigarette manufacturers, Freddie Noon, the thief, is now invisible. This condition has clear-cut advantages for a man in Freddie's profession, but now everybody wants a glimpse of Freddie. But Freddie doesn't dare show his face, his shadow, anything. Because Freddie Noon has gotten a taste of invisibility--and he can't quit now.

From Publishers Weekly

Yet another variation on the invisible-man notion doesn't sound like a promising prospect, but if any author can wring some fresh fun out of it, Westlake's the one. He doesn't fail. Freddie Noon is a sharp, likable burglar whose mistake is to break into the offices of two doctors doing so-called research for the Tobacco Institute. Catching him, they make him a human guinea pig for one of their formulas, and -- meet disappearing Freddie. Naturally, his life as a burglar gets much easier, but his girlfriend, Peg, isn't too comfortable with an invisible lover. In no time, Freddie is on the run: the Institute wants him for its nefarious purposes, the doctors want to study him further and a corrupt cop has his own reasons for pursuit. How Freddie and Peg run rings around the opposition, in New York and at an upstate hideaway, is the stuff of glorious Westlake comedy, in which Freddie's invisibility is merely one element in a caper full of hilarious characters, crackpot conversations and narrative sleight-of-hand.