This violent gangster-noir is dominated by Broderick Crawford as a tough cop who goes undercover among New York longshoremen to investigate criminal activity- including murder- by the union. This is three years before On the Waterfront. So HUAC would appreciate its politics, even if it does feature a corrupt policemen.
The plot is driven by the search to expose the gang boss. Which will come as a surprise, and the jeopardy of the special agent makes this a potent thriller. The clunky wisecracks which Crawford has to constantly spit out are a weakness, but his aggressive, kinetic performance supplies the film's energy.
He created variations on this character for the rest of the decade. There are familiar faces in minor roles. Charles Bronson is an uncredited dockworker and Ernest Borgnine a supercilious heavy. Best of all, Neville Brand re-runs his schtick as the sneering, sadistic goon. Somehow he gets better dialogue than anyone else.
There is expressionism and the action is melodramatic, but it's the look of grainy realism which impresses. This is a dirty waterfront of desperate men. The female roles are peripheral. Once the postwar vogue for classic noir began to fade, the gangster picture returned. Though this isn't well known, it's among the more successful.