Albert Finney is a would-be comedian and general smartass, places an ad in the paper announcing himself as a private eye and immediately gets in over his head. It’s a good premise, because at no point is Finney an actual detective – when he finds a gun at a crime scene, he keeps playing with it and shows it off to everyone he sees.
Finney’s brother William (Frank Finlay, one of Lester’s Musketeers) is the type of serious businessman who also knows how to dispose of a dead body, and the brother’s girl who used to be Finney’s girl is his Charlie Bubbles costar Billie Whitelaw. Clues lead to an occult bookstore lead to a heroin trade. There’s a hot library girl, some racism, and some unusually good dialogue.