After Johnny Clay has recruited a crew and meticulously prepared his hold-up, an accomplice lets the gangster into the staff changing room at a racetrack. Wearing a clown mask and armed with a rifle, he makes them turn over the track's takings.
Hiding behind a handkerchief in the novel, the gangster uses a mask in the film. The accessory of course has a narrative function – allowing the thief to hide his face and prevent any identification by witnesses – but it has a symbolic function as well. By going through the door marked "No admittance" thus disguised to commit his hold-up, Johnny Clay makes a mockery of the law, openly laughing at it.
An ironic transgression of the usual codes and assignations: how could one imagine that such brutality bear the face of a clown, a character that is, most often, comical and inoffensive? Here, the mask represents a star of the American circus: Weary Willie. Created and portrayed since the 1930s by the clown Emmett Kelly, Weary Willie is the embodiment of the unlucky hobo, a character who became popular in the United States with the Great Depression.
Thanks to the Weary Willie mask, the protagonist earns sympathy. Kubrick uses it to maintain the viewer's empathy towards Johnny Clay, presented as a soft-hearted gangster aspiring to quit the "trade". But although the clown mask counterbalances the violence of the hold-up man's gestures and words, it also prefigures his future failure: the gangster sharing the fate of the hobo.