When Nancy and her friends see a beam of light coming from an abandoned lighthouse, they notify the sheriff. Because the light has disappeared, he thinks that they're imagining things. Nancy sets out to expose the strange mystery that surrounds the lighthouse.
Soon after Nancy, Bess, and George check into their cottage at Opa Tourist lodge, they discover the popular tourist retreat is a hotbed of deception and crime.
Nancy and her friends establish headquarters in a seaside yacht club to investigate strange happenings in a book store and the disappearance of a marble statue.
While helping the police find the owner of a mysterious house with a crooked staircase and an unpredictable robot, Nancy Drew, teen detective, also helps capture a swindler.