Peter Diamond, the traditionalist dinosaur of Bath CID, finds the low murder rate in the city a touch frustrating, so he decides to check whether a couple of suicides which his colleague is investigating have been accurately classified. On the outskirts of the city a woman is found unconscious in a hospital car park, but when she recovers she can't remember who she is or how she came to be there.
Once again Frank and Joe Hardy accept the challenge of a puzzling case when their famous detective father asks the boys to assist him in tracking down a notorious jewel thief and his accomplices. The trail leads to the outskirts of the Hardy's home town and to a weirdly guarded mansion on the old Perth estate.
