This second film adaptation of Agatha's Christie's classic murder mystery is loosely based on the novel and on the children's nursery rhyme of the same name. Eight strangers and a husband and wife household domestics are invited to spend a weekend in a remote Swiss mountain chalet by an unknown host. After it is revealed that each of them is responsible for a murder, they are killed off individually in accordance with the nursery rhyme.
Although some of the murders and descriptions of the guests' crimes do not follow the original rhyme, this was obviously done to update the movie for a 1960s audience. The two women guests were made younger and hipper; one was played by Shirley Eaton who later played Jill Masters in Goldfinger.
More curious was the casting of Fabian as a fading, obnoxious entertainer. If the purpose to allow the viewer to cheer his demise, it succeeded.
The major failing is one that I have with many book adaptations: the ending was changed to a more positive one. Not everyone dies in this version which is at odds with the very downbeat ending of her original mystery thriller.