Melanthos Moon is a San Francisco art and antique dealer who manages to hijack a large supply of the special paper used to print U.S. Currency. He then arranges to spring from Leavenworth prison master counterfeiter Hans Dreiser to engrave the plates to produce the money. Eliot Ness and the Untouchables are soon on to him having followed Moon's henchman Benny Joplin back to his Oakland, California home. With the phony money available, Moon then approaches Chicago mobster Frank Nitti with an offer of $100 million split 50/50 with Nitti distributing the cash.

Eliot Ness sets out to bring down Frank Makouris, who controls New York's Fulton Fish Market by intimidation and murder and who is responsible for the price of fish going up nearly 50%. Frank's boss, gangster Joe Kulak, tells Frank to lay low until Ness leaves, but Frank ramps up his terrorizing of the market, until Kulak is forced to throw a low-ranking hood to the feds as a sacrificial lamb in order to take the heat off himself. Unfortunately, it doesn't work out as planned.