James Cagney runs a shady missing-heir tracing service, occasionally providing phony heirs in order to collect his fee. He suffers a tinge of jealousy when he takes a gander at the offices of a legitimate tracing firm, where his former girlfriend (Bette Davis) has taken a job. Jimmy soon learns that the reputable organization's boss (Alan Dinehart) is more crooked than Jimmy ever was, but he can't convince the girl of this fact. Using his own street smarts, Cagney exposes the "honest" heir tracer and agrees to go straight if his girl will come back to him. At the time Jimmy the Gent was filmed, James Cagney was getting tired of the formula pictures being handed him; rather than go on suspension, he expressed his displeasure by shaving his hair almost down to the bone, which is why he appears in this film with an uncharacteristic buzz-cut.