Established fans should welcome this seventh mystery (after 1999's Endangered Species) featuring Robin Light, the hard-drinking, sloppily dressed, heavy-smoking amateur sleuth and exotic pet-store owner from Syracuse, N.Y., but the uninitiated may find the plot tortuous and the plethora of characters too hard to keep track of. Robin faces a double challenge: locating a teenage runaway in nearby Cazenovia; and investigating an animal psychic, Pat Humphrey, whom three siblings suspect of defrauding their elderly heiress mother, Rose Taylor. Humphrey has won a place in Rose's heart (and will) by locating Rose's "kidnapped" cat; now Rose's much-younger husband and her lawyer hover over the old lady protectively. In the process of discovering that just about all the principals harbor secrets (one of Rose's children is a heroin addict, another a thief and transvestite), Robin is punched into unconsciousness, shot at several times with a rifle and held at knife-point. She also travels between New York and Wolfe Island, Ont., with no mention of Canadian or U.S. immigration or customs. On one page an automatic pistol turns into a revolver, while elsewhere a string of pearls, later described as knotted and hand-strung, breaks and cascades to the floor. Such careless slips won't bother most readers, but they do suggest why Block has yet to join the first rank of authors writing about contemporary female detectives. (July 9)