A young man is in hospital, critically ill after a caving expedition under the Moors close to Rochfield. His fiance discovers that he has ingested a deadly toxin. There is a race to find the cause. Once the cause is known, she searches for the source and gets too close to an illegal dumping operation. She disappears. The police in her home town fail to discover her whereabouts and, in desperation, her fiance turns to Rochfield CID in the hopes that...