The enduring power of this silent-era comedy classic from director/star Buster Keaton can be ascertained simply by recognizing how often its central concept has been cribbed, most notably by writer/director Woody Allen for The Purple Rose of Cairo (1985). Keaton is a cinema projectionist who dreams of being a famous detective, like Sherlock Holmes.
In love with a beautiful girl (Kathryn McGuire), he presents her with chocolates and a ring, but another suitor (Ward Crane) also vies for her affections. The projectionist unsuccessfully tails his romantic rival, a deceitful sort who has stolen a watch from the girl's home and pawned it to buy her a larger box of candy.
Falsely accused of the crime by his girlfriend's family, the heartbroken young man falls asleep at work while exhibiting a movie. He dreams that he walks into the screen and interacts with the film's characters -- now the players in the stolen watch imbroglio.