***SPOILERS*** Unlike his honest and ethical late father coin dealer Vince Hagopian Jr., John Saxon, is all out for making it big in the most unethical as well as murderous ways. Targeting coin collector John R. James, Joseph Cotton, for his latest victim he uses young and naive Karen Pearson, Belinda Montgomery, to get a job as his cleaning woman as well as part time private secretary to case out his coin collection that includes a 1907 gold double eagle the only one of it's kind, worth $22,500,00, on the market. That he plans to rob while the old and wheelchair ridden guy as he's taking his evening sabbatical.
Vince has already proved what a creep he is in having two of his accomplices Ernie Walker, Jamie Farr, and his diabetic assistant Tommy Hendriksen, William Gray Espy, knocked off when he had no use for them. With Tommy doing in Walker and Vince in return having Tommy die due to an overdose of insulin you can just guess that he'll do the same thing to Karen after she outlives her usefulness to his plans of making it rich on Mr. James dime or gold coins.
It's our two hero in the series Det. Let. Mike Stone, Karl Malden,and his youthful assistant Inspt. Steve Keller, Michael Douglas, who figure things out as well put an end to Vince's plans. That's by finding that he's been counterfeiting new gold coins and replacing them with rare and valuable minted ones that he plans to replaces Mr. James's collection with. This soon backfires on Vince when after she got religious Karen planed to expose his seedy operation to the police as well as her boss Mr. James that he planed to rob. Knocking Karen unconscious, with a wack across her face, Vince now planned to make his getaway with Mr. James's, who's taking a nap in his study, coin collection only to run into a firing squad lead by Stone & Keller from the SFPD that put him on ice at the local city morgue.