After his brother Charles dies in mysterious circumstances, Harry Spaulding (Ray Barrett) inherits his cottage in the Clagmoor Heath, Cornwall. He quickly moves in with his new bride, Valerie (Jenifer Daniel), with a view to finding out what happened. However, he is shunned by the locals apart from the village publican, Tom Bailey (Michael Ripper), who befriends him. The only other resident in the vicinity of the cottage is Dr. Franklyn (Noel Willman), the owner of the nearby Well House. He lives with his daughter Anna (Jacqueline Pearce), who is attended by a silent Malay servant (Marne Maitland). Anna is a strange girl who seems to be harbouring a secret. Her father treats her contemptuously and does his utmost to keep her confined to Well House. When the local village eccentric, Mad Peter (John Laurie), dies in a similar fashion to Charles Spaulding, both Harry and Tom decide to take matters into their own hands and to investigate further.