"The Mob" (1952)

Unlikely leading man Broderick Crawford does a fine job in this waterfront film noir. He witnesses a cop killing and must go undercover among mob infiltrated dock workers to ferret out the crooked leader of the syndicate who did the dirty deed. There's a lot of heavy drinking, gunplay, and rat-a-tat tough guy dialog before the surprise unveiling of the mob boss, and it's well worth the time.