A television version of the screenplay by Wilder and Kurnitz, adapted by Marcus, based on Agatha Christie's stage play.

A phlegmatic London barrister defends one Leonard Vole, a ""nice, harmless chap"" who's on trial for the murder of a widow who had taken a shine to him. The circumstantial evidence against Vole is strong, especially since he's unemployed and stands to inherit a considerable sum from the victim. And to further complicate the defense, the only person who can provide an alibi is Vole's wife Christine, who has agreed to be a witness for the prosecution.

The movie follows the medical charts of Sam Alden, a spunky, personable 17-year-old from a close-knit family who is suddenly stricken with coughing spasms, cold sweats, and shortness of breath. His alarmed parents take him to an array of doctors for tests that lead to a dire diagnosis of a degenerative heart condition which could kill him within five years. Shocked and scared, and getting sicker all the time, Sam undergoes a transplant, then faces an even more grueling ordeal as doctors battle to keep his body from rejecting the new organ.