Based upon an idea by Broadway columnist Mark Hellinger, The Roaring Twenties opens during World War I as doughboys Eddie Bartlett (James Cagney), Lloyd Hart (Jeffrey Lynn), and George Hally (Humphrey Bogart) discuss what they will do when the war is over. Bartlett wants to go back to repairing cabs, and Hart yearns to be a lawyer, but it becomes clear that Hally has less reputable plans in mind for himself. Come the end of the war, things are not as easy for veterans like Bartlett as they should be. He is unable to get his old job back and ends up driving a cab for little money. One night he is asked to deliver a package (which turns out to be whiskey) to an address that turns out to be a speakeasy. This starts him on a life of crime, as he gets deeper involved as a bootlegger. Things are not made easy by a rival bootlegger -- who turns out to be Hally. The two join forces and prosper. Hart shares in their prosperity, as Bartlett engages him to take care of his legal matters. Unfortunately, Hart is also interested in Jean Sherman (Priscilla Lane), a young woman that Bartlett has had an eye on for quite some time. He loses her to Hart at about the same time that his criminal empire crumbles, and he is reduced to driving a cab again while Hally continues to prosper with his ruthless ways. Eventually, Hart -- now a crusading prosecutor -- runs afoul of Hally, who tells Jean that he will kill him if he doesnt change his ways. Jean begs Bartlett to intercede with Hally; because he still is carrying a torch for her, Bartlett agrees -- but by doing so, he may have signed his own death warrant. ~ Craig Butler, All Movie Guide