During his heyday, Harry Agensky (KIRK DOUGLAS) was once known as the "Polish Prince," the welterweight champion of the world. But that was many years ago, and Harry now finds himself living with his son, Moses (KURT FULLER), and daughter-in-law, Roseanne (JUNE CHADWICK), in their Canadian home. Harry has recently suffered a stroke, and despite a strong recovery and his dedication to his vocal therapy exercises, he fears that his family will soon put him into a nursing home.
Wanting to retain his independence, Harry often talks about some "magic diamonds" a Reno mobster named "Duff the Muff" left for him after throwing a fight. Of course his family thinks he's crazy, but he gets the chance to prove his sanity when Lance (DAN AYKROYD) his other divorced, newspaper columnist son, and eighteen-year-old grandson, Michael (CORBIN ALLRED), show up to take Harry on a weekend trip. Although they're reluctant to believe him, Lance and Michael, who get along with each about as well as Lance does with his stubborn father, finally agree to secretly drive Harry back to Reno in search of the diamonds.
During their travel, the three generations of Agensky men try to understand each other. Finally arriving in Reno and still searching for "Duff" and those diamonds, they make a pit stop at local brothel. There, Michael gets his first taste of sex with a buxom hooker by the name of Sugar (JENNY McCARTHY), while Harry meets the madam of the house, Sin-Dee (LAUREN BACALL), an older woman who sympathizes with him. As the grandfather, father and son continue on their quest, they begin to understand and better appreciate each other.