The Stanleys are back from Italy (The Famous Stanley Kidnapping Case), more-or-less resettled in the Westerly House (The Headless Cupid)—where David, a shaky 13, doesn't know what to make of family-fantasizer Blair's nightly jaunts to see a dog in the yard. . . or how to deal with hulking, taunting classmate Pete Garvey. Adolescing stepsister Amanda is an enigma too—admiring Pete's physique, punching him out to protect David, looking sympathetic? pitying? And why does Pete start hanging around? But the problem that grows ever-bigger is Blair's dog. Dad and stepmother Molly quarrel over his clamp-down on Blair's "fantasizing." Six-year-old Blair's twin Esther, and resident-snoop Janie, huddle with him. A neighbor's smokehouse is broken into—only maybe by two escaped cons. On a spooky night—when the cons have just resurfaced, and Dad and Molly are out—the older children discover one thing at least: there is a real dog, a monstrous, gentle Irish wolfhound, whom the little children have named Nightmare. Further sleuthing by Janie (who spotted the breed in a book) explains his old bullet-wound and his fear of grown men: guard-dog training, by a vicious owner. All the more reason, then, to conceal Nightmare from Dad—who's already vetoed the idea of a dog, who'll feel obliged to contact the owner. The ensuing conspiracy is an all-hands, full-time operation. Nightmare spends nights with Blair and David, behind a warily locked door. (Once, Molly does demand admittance.) Days, he disappears—where? Massive as he is, he must be massively fed—hence the kibble caper. Then, for a couple of nights, he doesn't show up; Blair steals off to search for him; David finds both of them—turning up the fugitive cons (sick, dejected), bringing them in, becoming an embarrassed/ pleased hero. Amanda has made her new sisterly feelings known. Pete, confiding his (transparent) interest in Amanda, tells the still-droopy David not to confuse fighting and courage. As for Nightmare, you know Dad won't be able to resist his oversized appeal, his part in the heroics, or Molly's good-natured teasing. ("How could an imaginary dog be a burden?") The family mix continues to work its charm, the personalities to unfold independently—with more to be seen or heard, it appears, of Blair's elusive friend Harriet.