Columbo (season 4)

Renowned exercise guru Milo Janus (Robert Conrad) runs a chain of successful gyms that operate under his name. But even his charm isn't enough to calm the anger of business partner and franchise owner Gene Stafford (Philip Bruns), who's found out how Janus overcharges his own corporation for equipment and supplies, depositing the profits in offshore bank accounts. When Stafford threatens to organize other victims of Janus and to go public with a class suit, which would leave Janus open to criminal and civil charges, Janus kills him, and makes it look like Stafford was trying to lift a weight too heavy for him. Collin Wilcox plays Ruth Stafford (the victim's distraught and often boozy widow, who thoroughly mistrusts Janus), Gretchen Corbett plays Janus's secretary, and Pat Harrington, Jr. is a sleazy business associate of Janus.

After years of marriage to his domineering and bitter wife Frances (Antoinette Bower), professional photographer Paul Galesko (Dick Van Dyke) decides to kill her. He hires ex-con Alvin Deschler (Don Gordon) to rent an isolated ranch house. Galesko persuades his wife to accompany him there and she grudgingly agrees. He ties her to a chair, takes photographs, then shoots her. He sets things up so that it will appear he is elsewhere when the pictures were taken. Galesko meets Deschler at a junkyard for a staged ransom drop. After shooting Deschler with a revolver, Galesko shoots himself in the leg with the pistol used in the first murder, then plants that gun on Deschler so that it will appear he killed the "kidnapper" in self-defense. JoAnna Cameron plays Galesko's assistant, with whom he is planning a romantic getaway. Michael Strong, Larry Storch, Vito Scotti, and John Ashton guest star as does Joyce Van Patten, playing a nun running a homeless shelter who assumes, just by looking at Columbo for the first time, that he is down and out and offers him food and a better coat.

Colonel Lyle C. Rumford (Patrick McGoohan), head of the Haynes Military Academy, an all-boys school, is told by Board of Trustees president William Haynes (Tom Simcox) that it must convert to a coed school as a solution to declining enrollment. Haynes, grandson of the academy's founder and once a cadet under the colonel, has furthermore decided to fire his hated former commandant. Rumford would rather not go that way. So he rigs a school cannon by blocking its discharge with a cleaning rag, then modifies the shell with a more powerful explosive so that the cannon will explode when Haynes fires it on Founder's Day. Rumford pins the "accident" on emotionally troubled cadet Roy Springer (Mark Wheeler), who had gun-cleaning duty. Rumford is trapped by Columbo due to his own fanatic sense of duty.

Final clue/twist: When Columbo gets suspicious about Rumford's almost maniacal attempts to find a bottle of prohibited cider, he learns how and when the cider was made. After finding the cider, Columbo asks Rumford offhand if he saw the cider before. When the victorious Rumford confirms, Columbo tells him, that he could've only seen the cider on the morning before the murder - within a small timeframe and only when standing by the cannon (because the cider wasn't there or visible before or after) - while Rumford claims he was asleep.

While aboard a Mexican cruise he takes frequently, auto executive Hayden Danziger (Robert Vaughn) has been having an affair with the ship's lounge singer Rosanna Wells (Poupée Bocar). When Wells threatens to expose their affair to Danziger's wife, Sylvia (Jane Greer), Danziger decides to get rid of Wells. To set up his alibi, he inhales some amyl nitrite to feign a heart attack in the swimming pool, so that he will be checked into the ship's hospital. During a lapse in security, Danziger dons a crewman's uniform, sneaks out of his hospital bed, and waits in Wells's cabin for her performance break. When Wells comes back, Danziger shoots her, plants evidence to implicate a band musician, Lloyd Harrington (Dean Stockwell), ditches the pistol and returns to the hospital before the doctors can find him missing. Columbo, who happens to be enjoying the same cruise with his wife, is pressed into service by the ship's captain (Patrick Macnee). Bernard Fox and Robert Douglas also guest star.

Harold Van Wick (Oskar Werner), the controlling, arrogant, gadget-obsessed president of Midas Electronics, has wired his estate-home with closed-circuit television cameras and video recorders. His costly fascination with gadgetry raises the ire of his mother-in-law Margaret Midas (Martha Scott), who owns the company. She orders him to resign his post by the following morning, or she will expose his philandering ways to his wife, her daughter, Elizabeth. Van Wick has already set in motion a scheme to murder her. He rigs his high-tech home security system and shoots Margaret when she is in the viewing field of one camera, feeding a recording of an empty study to the guard monitoring the estate's rooms. Having already forced open a window and planted footprints outside it to make the murder look like the deed of a burglar, he then uses a timer to play back the tape of the shooting to the gatehouse guard's monitor to make it look like Margaret was shot by an intruder after Van Wick had left the house for a party. Gena Rowlands portrays Van Wick's beautiful, wheelchair-bound wife. Robert Brown played Arthur Midas, Margaret's son and Elizabeth's brother.

Psychiatrist Dr. Mark Collier (George Hamilton) is expecting to meet his beautiful married lover at her isolated beach house in the empty season. However, he finds her husband, Carl Donner (Stephen Elliott), present as well. Carl prevented his wife, Nadia (Lesley Ann Warren), from calling Collier to warn him off. The two men get into a violent confrontation over Collier's affair and drugging of Nadia, who is also one of Collier's patients. Overmatched, Collier grabs a fireplace poker and kills Carl with one blow. While Collier is speeding away, he has to hit the brakes to avoid a blind man walking with his dog. Collier's car bangs into one of the posts along the long driveway. He concocts a cover story involving a home robbery gone astray. But when Columbo makes clear Nadia's story is not credible and the increasingly unstable woman appears about to break, Collier hypnotizes her into taking a deadly swan dive into an empty swimming pool from her fifth-story balcony.