``Funny how things start out,'' muses wannabe Yorkshire shamus Sam Turner. ``You take on a matrimonial case and find you're tracking an international serial killer.'' In fact Sam's first case is deceptive from the word go, when Terry Deacon, hearing Sam tell an AA meeting that he's a detective, hires him to follow his wife Jane, whom he suspects is cheating on him. She isn't; instead, Terry has taken trying to get her followed as a way of hiring a bodyguard for her on the cheap. By the time Sam finds that out, though, Terry himself is already dead, stabbed in a frenzy and left with a sign (``Terry Deacon deserves to die'') that connects his murder to a rash of killings of former housemates of New Zealand poet Graham East. The police think Graham's their man, but he's dead, too, killed by his girlfriend Frances Golding, who's now convinced his life was ruined by people who aren't her and transformed herself into his avenger. The motley crew Sam assembles to track down the killer--old biddy Celia Allison, pool-hall buddy Gus, and a homeless kid called Geordie--have a raffish appeal, but unbalanced, threatening Frances wears out her welcome long before the end of this slender tale. Newcomer Baker's agreeably clipped delivery hides the fact that most of his surprises are exhausted in the early going.