Broderick Crawford is Damico, a police detective that is outwitted by a gangster named Blackie Clay, and is suspended from duty.
This is all a ruse to have him go undercover as a longshoreman in order to find Clay and expose the waterfront rackets. Damico makes a big stir on the waterfront, so much so that he is taken to meet the head man in a very short time.
The top man is Joe Castro, played by Ernest Borgnine and his top henchman is Gunner played by Neville Brand in a performance I will never forget. Damico works his way in, but finds he may buy the farm at any moment as nobody appears to be what they seem in this film. His only friend seems to be a man named Thomas Clancy, played by Richard Kiley.
If you love movies in general seek this one out and watch it.