Jenny Jakes and her mother, a famous mystery writer, travel to San Antonio to see their cousin, Arnold Harmony, who's made his fortune in the chocolate business. Harmony, an eccentric millionaire, wants his will read publicly before he dies; since everyone wants a piece of the pie, this announcement causes quite a stir. When Harmony's son is murdered just before the reading, Jenny's mother decides to spring into action as a real-life detective. But Jenny's mother doesn't have a clue about solving a real crime, so it's up to Jenny to use her wits, not only to save her mother's reputation, but also to keep herself from being killed.