A chemist decides to kill his uncle in order to prevent him selling the family business to a conglomerate in exchange for a seat on the Board of Directors, by concealing a time-delaying explosive device inside a box of his uncle's favourite cuban cigars.
Stanford Chemicals CEO David Buckner wants to sell the business, but he is overruled by several people: his wife Doris, company lawyer Everett Logan, and his nephew Roger, the lighthearted young genius whose late father founded the company. But he has a plan: he has uncovered some very embarrassing and illegal past activities on the part of Roger. He demands that his nephew change his aunt Doris's mind about the sale, or he'll tell Doris about all the nasty things her precious Roger has done. But Roger is one step ahead of him, and initiates a plan to murder his uncle with dangerous explosives. Unfortunately for him, he didn't count on Lieutenant Columbo investigating Buckner's "car accident." The Lieutenant quickly suspects Roger, and puts together a web of evidence to trap the young scientist in his own lies.
Pressured to give up his birthright, a chemical company heir enacts a clever plan to get rid of his blackmailing uncle and take over the family business. But Lt. Columbo suspects the man's death was not just a tragic accident.
- An explosion kills an executive as he talks to his wife over his car phone and a company attorney is suspected.