 When a well-known New York businessman is found dead in the penguin pool of a local zoo aquarium, Inspector Oscar Piper is called in to investigate the murder. At first, Inspector Piper is put off by one of the eyewitnesses, a schoolteacher named Hildegarde Withers, who seems overly inquisitive and meddlesome. But as the investigation progresses, Inspector Piper forms an uneasy alliance with the shrewd Miss Withers, whose insights and advice help to crack the case.