Contrary to popular opinion, the best moment in The Public Enemy isn't when Jimmy Cagney shoves a grapefruit in his girlfriend's face—it's the moment Chicago gangsters Tom Powers (Cagney in a career-making performance) and his buddy Matt Doyle (Edward Woods) hear that one of their own is dead, not by a rival gangster, but from being thrown off his horse. Even when Powers and Doyle march into the stable in a welter of cold fury, you don't quite believe they're actually going to execute the horse, and yet they do. In a film that begins and ends with high-toned messages about the evil hoodlums do to society, this was likely originally intended to illustrate the rapacious inhumanity of these gangsters (a horse?), but there's no denying its intrinsic black comedy. Studio-imposed moralizing aside, this is a film with a wicked sense of humor—witness the scene in which a swishy haberdasher feels up Cagney's bicep while measuring him for a suit—that makes up for an occasionally stale plot.
Powers and Doyle are childhood best buddies, growing up petty crooks in the teeming Chicago tenements of the early 20th century and graduating to big-time crimes once the local mob is handed the sweet gift of Prohibition. Director William A. Wellman brings a sociological bent to his depiction of their milieu, using old newsreel footage of the city, carefully marking the passing of the years and paying close attention to the particulars of the characters' working-class Irish surroundings. There's a clean arc to the story as we follow Powers and Doyle from the "social club" where the neighborhood kids do odd crimes for the resident Fagin character, Putty Nose, to their first involvement with burgeoning bootlegger Paddy Ryan, to them living the high life as smart-dressed hoods and the final showdown where Powers stalks into enemy headquarters (a justifiably famous shot where he practically walks into the camera), a revolver in each hand and a killer's stare on his face. The nature of the film's rise-and-fall plot, however, can seem overly premeditated at times, and borders on the simplistic.
The Public Enemy starts by telling its audience that it does not mean to glorify the criminals that it portrays, and unlike some other gangster flicks of the 1930s, it actually doesn't. Although the crook that Cagney plays here has a definite thuggish cool, he's repeatedly shown to be such a thickheaded animal that he doesn't register as much of an antihero (the only thing helping him is that none of the other characters register much in the way of personality, either). He's the kind of overzealous idiot gunman who Bogart would have mocked relentlessly in The Big Sleep. Even so, there's little denying the power of Cagney's presence, from the first moment he's on screen, he radiates such a brash Fenian cockiness you can imagine kids at the time flocking out of the theater and cocking their caps just like him. It's a performance so perfect in its intensity that any other quibbles about the film ultimately recede into insignificance.