Buster Keaton perfected his Great Stoneface persona over years in vaudeville and dozens of shorts dating back to 1917. By Sherlock Jr. he was at his peak. He plays a projectionist who aspires to be a detective. Unfortunately he is fitted up by his unscrupulous rival for a girl to appear the thief of her father's pocket watch.
Then Buster falls asleep while showing a film about a jewel thief, and dreams that he enters the screen and solves the crime. As it is a dream, the events become increasingly surreal. Other silent comics used incongruous back projection, but here Buster interacts with his fantasy, distorting the events.
It's a brilliant set up. Keaton was also an extraordinary physical comedian, and the action is full of amazing acrobatics. Like when he stands on a huge water-pipe as it swings across the road and deposits him in the passenger seat of a getaway car. Which actually broke his neck...
The contrast between Keaton's deadpan exterior and his outrageous escapades is the key to his comedy. It is hard to watch Keaton's extravagant, show-stopping stunts and not be overwhelmed by his ambition and craft. He is the most enterprising and gifted of all the '20s comedians. Sherlock Jr. is his masterpiece.
Despite a thin plot, this silent movie packs a punch nearly 100 years later with wall-to-wall shocking stunts.