The film begins with a powerful statement that serves as a bold indictment against the lawlessness of gang rule, urging individuals to take action because the government belongs to the people. Set in the gritty backdrop of Chicago's 22nd Street, we witness a man tidying up a nightclub while a group of men chatter about Johnny Lovo seeking to make a big move on the south side. This man, known as Big Louis, appears to be a figure of influence but meets a grim fate as a shadowy figure enters and gunned him down before escaping. To avert any trouble, the club's cleaner dons his jacket and quietly slips away.
Meanwhile, in the bustling office of a newspaper editor, news breaks that Big Louis Costello has been murdered, signaling the onset of an impending gang war. With C. Henry Gordon portraying the detective Guarino, we see the police make their rounds as they spring into action. At a local barbershop, tension brews as Tony Camonte (Paul Muni) jokes sarcastically with the officers, even lighting a match on one of their badges, which leads to his arrest. Following his release courtesy of his crafty lawyer, Fleming, Tony visits Johnny Lovo (Osgood Perkins), who is accompanied by his flippant girlfriend Poppy (Karen Morley). Johnny offers Tony a sum of cash, promising him a raise as they plan to dominate the south side’s territory.
Not one to shy away from ambition, Tony expresses interest in the north side, mistakenly thinking that he can take on the likes of O'Hara. Lovo quashes his dreams, insisting that they lie low until after Louis' funeral. As the power struggle unfolds, Tony’s ambition surfaces—he dismisses Johnny’s warnings, claiming he has little to fear, stating, “Do it first, do it yourself, and keep on doing it.”
Later, at home, a family confrontation arises when Tony discovers his sister Cesca (Ann Dvorak) in a compromising situation, prompting a heated argument over her lifestyle choices. Cesca, who is spirited and carefree, insists on living her life independently even as their protective mother warns her not to get entangled in Tony's criminal undertakings. The film captures a motif of cash and chaos, showing the insidious nature of Tony’s influence on his family.
As the month rolls on, Tony and his crew bravely assert their presence by storming the deceased Louis’ club, utilizing violence to instigate control. A shootout at the Shamrock leads to further bloodshed, heightening the ongoing tension within the underworld. Daring and brash, Tony seeks out love while navigating through a maelstrom of gang rivalries and law enforcement.
We then witness the chilling machinations of Gaffney (Boris Karloff), a cunning British crime lord, who aims to dispose of Tony amid the burgeoning violence. As Tony’s power grows, so do the dangers that lurk in the shadows. Paranoia creeps into his psyche, and he becomes increasingly ruthless—at one point, escalating a conflict with a rival gang resulting in mass casualties, reminiscent of the infamous St. Valentine's Day Massacre.
The climax builds around Tony's tumultuous relationship with Poppy and the violent path he treads to secure his empire. Flashes of familial strife appear, especially when Cesca dares to pursue her own love life, spurring tragic repercussions. The bitter climax reaches a boiling point, culminating in violent confrontations, betrayals, and the devastating fallout that engulfs his world.
Ultimately, Tony's tragic end is captured as he finds himself cornered during an explosive encounter with police, seeking solace in his sibling's company only to find himself lost in a storm of chaos. In a heart-wrenching finale, Tony's sister suffers a devastating fate, and as he confronts the authorities, the film concludes on a haunting note, with a poignant echo of the phrase “The World is Yours.” This emotional finale showcases the tragic consequences of Tony’s ascent and the personal costs of a life steeped in violence, leaving audiences with profound reflections on crime and its toll on humanity.
