Nove Ospiti per un Delitto is a mediocre giallo in the tradition of Agatha Christies And Then They Were None. Nine members of the same family go to an island, where nobody lives - but the head of the family (Arthur Kennedy) owns a nice house there. Problem is that he and his three sons keep a dark secret, and this dark secret begins to haunt them as soon as they are on the island. One by one they fall victim to a mysterious killer... (IMDb)