A homicidal killer is living snugly in a London roominghouse, his thoughts (which don't reveal his identity, of course) interweaving with Babson's portrait of the whole roominghouse community. Maude Daneson is the landlady, helped out by artist Iris Loring, and the guests (suspects) are an assortment of retired loners, working singles, and foreign students--all of them currently in the grip of last-minute Christmas fever, exacerbated by Maude's plans for a big Christmas dinner. Meanwhile, the killer's bizarre and senseless murders go on, far away from the house, with much frustration for Detective Superintendent Knowles. But then the maniac commits a crime closer to home, and Knowles is on his track--and the inspector will wind up as the most welcome of guests at the Christmas table. . . . In Babson's skilled hands, the old which-one's-the-homicidal-maniac? chestnut flies again--for a fast-moving, one-sitting treat that's marred only by a just-slightly saggy climax.