A movie theater projectionist and janitor is in love with a beautiful, loveable girl. However, he has a rival, the "local sheik." The sheik steals and pawns the girl's father's pocket watch and blames the projectionist, so he is banished from the girl's home.

While showing a film about the theft of a pearl necklace, the projectionist falls asleep and dreams that he enters the movie as a detective, Sherlock Jr. The other actors are replaced by the projectionist's "real" acquaintances. 

Originally titled The Misfit, production began in January 1924 in Los Angeles. Keaton later said that his character walking onto the screen and into a film was "the reason for making the whole picture...Just that one situation." After previously casting her in Three Ages, Keaton cast Marion Harlan as the lead actress, but she became sick and was replaced by up-and-coming Keystone Studios actress Kathryn McGuire, who had previously starred in The Silent Call and was a Wampas Baby Star of 1923.

The production included one of Keaton's most famous on-set accidents. In a scene where Keaton grabs a water spout while walking on a moving boxcar train, the water unexpectedly flooded down on Keaton much harder than anticipated, throwing him to the ground. The pain was so intense that Keaton had to stop shooting later that day, and he had "blinding headaches" for weeks afterward but continued working, having a well-known high threshold for physical pain. 

Sherlock Jr. was also Keaton's most complicated film for special optical effects and in-camera tricks. The film's most famous trick shot involves Keaton jumping into a small suitcase and disappearing. Keaton later said that it was an old vaudeville trick that his father had invented, and he later performed.

Keaton depicted an early example of a film within a film in the dream sequence. Keaton later explained that this stunt was achieved through the use of lighting. Keaton and his cameraman were able to do this by using surveyors' instruments to position Keaton and the camera at exactly the right distances and positions to support the illusion of continuity.

In 2005, Time named Sherlock Jr. as one of the All-Time 100 Movies. Film critic Dennis Schwartz wrote that Sherlock Jr. is "one of Buster's superior silent comedies." In 2012, it was ranked number 61 in a list of the best-edited films of all time as selected by the Motion Picture Editors Guild members. It was a major influence on Woody Allen's 1985 film The Purple Rose of Cairo.

Sherlock Jr. was also Keaton's most complicated film for special optical effects and in-camera tricks.

The Soundtrack

Caspervek's Soundtrack for Sherlock Jr. follows the band's usual pattern of scoring slapstick comedies, alternating swing, and classic jazz and adding, this time, some twists on the detective movie music style.