Sherlock Jr. is a 1924 American silent comedy film starring and directed by Buster Keaton and written by Clyde Bruckman, Jean Havez, and Joseph A. Mitchell. It features Kathryn McGuire, Joe Keaton, and Ward Crane.

Plot

Buster Keaton stars as Projectionist, who moonlights as an amateur detective. When the cinema is empty, he reads the book How to be a Detective. He is in love with The Girl (Kathryn McGuire) but has a rival, "The Local Sheik" (Ward Crane). Neither has much money. He finds a dollar note in the garbage he swept up in the lobby. He takes it and adds it to the $2 he has. A woman comes and says that she lost a dollar. He gives it back. But then a sad old woman also says that she lost a dollar, so he gives that also, leaving himself with $1. A man comes and searches the garbage and finds a wallet full of money. Projectionist buys a $1 box of chocolates, all he can afford, and changes the price to $4 before giving it to the woman he loves at her house. He later gives her a ring.