The film alternates between 1957, when Martin & Lewis-like comedy team Lanny Morris and Vince Collins are at the height of their success, and 1972, when journalist Karen O'Connor is determined to unravel the mystery of a young woman who was found dead in their hotel suite. Immediately after hosting a 39-hour-long polio telethon in a Miami television studio, Morris and Collins fly north to discuss opening the showroom in a new Las Vegas hotel constructed by mobster Sally Sanmarco. In their Atlantic City hotel suite, the body of college student Maureen O'Flaherty is found in a bathtub filled with water, but since both men were en route to the hotel at the time she was murdered, neither is thought to be connected to the crime. Shortly after, their partnership is dissolved. Fifteen years later, Karen - who as a young polio survivor met the team at the telethon - becomes part of a $1 million deal to ghostwrite Vince's autobiography, a project complicated by the fact she keeps receiving anonymously sent chapters from a book about the one-time duo Lanny himself has written. She first meets Lanny, accompanied by his faithful valet Reuben - on a transcontinental flight, during which she introduces herself as Bonnie Trout, the name of the best friend with whom she's trading apartments. The two meet for dinner at a Chinese restaurant and later become intimate in Lanny's hotel room. The next morning, Karen awakens to discover Lanny checked out without saying goodbye. She later meets Vince and, using her own name, begins to interview him for the book. Complications arise when Vince invites her to dinner at his Los Angeles home and she learns Lanny will be joining them as well. She abruptly excuses herself but meets Lanny in the driveway. As the two are talking they are confronted by Vince, and Karen's masquerade is revealed. Vince agrees to continue to cooperate with the book, but he has an ulterior motive. Plying Karen with wine and drugs, he manipulates her into having sexual relations with an aspiring singer named Alice and photographs the two in compromising positions. He threatens to use them if he's displeased with what Karen writes but, undaunted, she continues her detective work and slowly pieces everything together until the real murderer's identity finally is revealed.