The ninth appearance of ""purrfect"" detectives Koko and Yum Yum and their doting housemate, millionaire newsman Jim Qwilleran, finds their sedentary summer plans--rusticating in a summer cabin in Mooseville--upset when the old place proceeds to fall apart and the carpenters who are hired to fix it disappear. The first to go is Clem Cottle, a reliable, soon-to-be-married sort. Next: the stupidly amiable, slothlike Iggy. Qwill's plumber, the lipstick-losing Joanna, admits that her dad, a carpenter, died peculiarly, as did a couple of other home-repairers. Meanwhile, Koko is tearing up certain articles in the newspaper and hovering over a trapdoor, while Qwill interviews octogenarian Emma Wimsey for his column and is left her diaries, stories, letters, etc., when she passes away. Eventually, Koko scampers through the trapdoor--locating Iggy--and Qwill finds an itemized list of carpenter victims. Emma's old diaries will reveal the murderer's motives, which--while psychologically plausible--seem deep indeed for this generally lightweight story. Mrs. Clinko, the maintainence dispatcher, is a chortling treasure; the cats are their usual magnificent selves. Overall: wonderful ambiance, so-so mystery.