While visiting her niece’s family in Chicago, Jessica gets an invitation to meet an amusement park tycoon who would like to adapt one of her books into a park. However when she refused to go along with his plan and he is found murdered later in the day, the police captain asks Jessica to aide in his investigation. At first she is hesitant to do so, but when the man’s widow also urges her to find the murderer, Jessica finally agrees to help out and soon figures out why the tycoon was killed.