Here, Canadian writer Wright--with interests divided between mysteries and psychological studies like Among Friends (1984)--manages to meld her two fascinations to good effect. As in several previous efforts, Wright features Staff Sergeant Karl Alberg of the Canadian Mounted Police, stationed in the village of Sechelt on the ""Sunshine Coast."" He's divorced and carrying about 15 extra pounds around the waist--a good man, but hardly a crack detective. One foggy January day, trouble hits Sechelt in twos: elderly Ramona Orlitzki vanishes from the local old folks' home, and Zoe Strachan, a hermitic woman living on the beach, reports the death of her brother, who's apparently fallen down the basement steps in a drunken foray toward the wine cellar. Ramona suffers from Alzheimer's, and Zoe has had psychopathic tendencies since birth, having recorded in childhood diaries the fact that she killed two neighbors when she was 12. Her brother becomes her latest victim when he tries to blackmail her with the diaries, leaving them in the care of his adopted son, Ken. Zoe takes custody of the boy, since a crazed second-sense tells her he knows where the incriminating documents are; and Ken flees to a cottage where Ramona's been hiding out. In the end, the poor old lady will have to sacrifice her life to save the child and get Zoe's childhood confessions to Alberg--who's been too sexually befuddled by Zoe to suspect her. Slow as a Pacific fog to develop, but, in the end, a gratifying mystery--thanks to the author's ability to size up all her characters' weaknesses.