In this thriller, Mrs Rendell portrays a 50 year old psychopath called Arthur Johnson. He fits exactly the definition of a psychopathic person. He is asocial, self centred, impulsive and suffers from an acute anxiety nurosis. He has a strong need to preserve an immaculate ego, he is paranoiac, fears retribution and has an urgent need to be thought well by all people. And men like him cannot be reassured because their belief in their own worthlessness is so intense. Self-confidence cannot be implanted in Arthur anymore at the age of 50. That's why he fears other people - they represent a menace to his own integrity - and so he lives in private isolation.
Characteristically for a psychotic mind, Arthur is unable to form emotional relationships and he has no social ways of coping with his frustrations. This is certainly why Arthur keeps a plastic shop window model in his cellar. This model is dressed in his Auntie Gracie's clothes - for him she is the image of a mother, wife, counsellor, housekeeper and sole friend - which Arthur delights in "strangulating" regularly at night.
A very good thriller which shows that Mrs Rendell understands how a psychopathic mind works and how it can go awry.