Radio personalities Larry Abbot and Vickie Pearle are stars of a mystery show. Since they announced their engagement, Larry has been plagued by speech problems and, seeking out an unconventional cure, he returns to his boyhood home, a mansion in the countryside, bringing Vickie along. Larry reunites with numerous family members, but discovers that there are sinister things afoot within the walls of the creepy estate.
When one of Regan's snouts complains that his girlfriend's recent suicide was murder, the flying squad detective feels compelled to investigate. He uncovers a conspiracy that reaches the heart of the government, and finds himself fitted up, suspended and under the scrutiny of Special Branch.