Exercise with Three Unknowns (1979)

A librarian with a sharp mind for murder, Aurora Teagarden is known around her small town as a master sleuth. When her friend Jane unexpectedly dies and leaves Aurora everything in her will, she also leaves a troubling murder mystery haunting her neighborhood. It is up to Aurora to piece together the clues—including a skull, its missing skeleton and a suspicious group of neighbors—and solve the murder before she becomes the unlikely killer’s next victim.

When a college student is found dead, English professor Amy uses her crime fiction expertise to unravel the case faster than detective Travis, who ends up working with Amy to catch the killer.

Faced with two false confessions and numerous suspects after a despised civil magistrate is found shot in the local vicarage, Detective Inspector Slack reluctantly accepts help from Miss Marple.

During her birthday celebration, Tess and Logan find themselves swept up in a world that isn't always what it seems when the headlining magician at the Magic Manor winds up dead.

Jenn buys an old reel-to-reel recorder at a garage sale only to find that it includes the sound of a man pleading for his life. When the former owner of the recorder, a retired therapist, is found murdered in a patient’s apartment, Jenn’s investigation leads to other patients whose love lives are more entangled than she was first led to believe.

Attorney turned therapist Hailey Dean is pulled into another investigation when a popular new dating app links multiple missing persons cases from around the city. Reuniting with her old team, Hailey discovers the potential dangers of online interaction, and must track down a killer before anyone else gets hurt.

When a priceless crown is stolen during a benefit gala held by the Lawrenceton library, Aurora and the Real Murders Club must investigate who would kill to get their hands on it.

Summer of 1945. The salute of the Great Victory died down and the country is gradually returning to peaceful life. From "fire yes into the fire" a young reconnaissance commander Volodya Sharapov falls, having come to the MUR for distribution, to the department for combating banditry. In the city the Black Cat gang rages, terrifying Muscovites. Captain Gleb Zheglov enters the fray with the bandits, for whom Sharapov soon becomes his right hand.

This film version was released before the premiere of the full two-part television version (The Adventures of Sherlock Holmes and Dr. Watson: The Twentieth Century Approaches). In this version the entire plot of the story Bruce-Partington Drawings was deleted.

During a murder hunt game at a country house, to which Hercule Poirot is invited as an "expert", a real murder occurs.