Bobby Marx is still slim at 16, two years after his Fat Summer (1977), and cool enough to be offered a summer job by the terrible Smith-Rumson gang, year-round residents (where the Marx family summers) who had made Bobby's previous two summers miserable. But Bobby's strict father, condemning ""bad company,"" decrees that Bobby will work instead with older sister Michelle at Happy Valley Day Camp. Kids who've met Bobby in Fat Summer will relate to the references and updating at the beginning, though they might have trouble recognizing Bobby. For others this gets off to a slow start, and the banality of summer camps and most camp stories works against the familiar opening-day introductions. Soon, however, cracks in the Happy facade become evident, personalities emerge, problems arise, and Bobby is up to his ears in initiations, conflicts, and responsibilities. (His first martini--and his second, third, and fourth at the same get-acquainted party--afford a funny-rueful preview of things to come.) He has his hands full with camp head Moe Bell's bratty, disturbed nephew Harley, and his arms full of Harley's sitter-cousin Slieila Bell, Bobby's opposite number in the typical Fifties' contest associated with ""making out."" When Harley burns clown part of the camp but the blame falls on Willie Rumson, now a brain-damaged zombie after a bout with prison therapy, Bobby faces a moral decision that his upbringing by a rigid father helps him resolve. (There are no summer rules.) Thus Happy Valley proves challenge and world enough for any summer. Along with the Fifties values, Lipsyte evokes the Fifties atmosphere of a summer community and pulls off another sharp, flesh-and-blood rendering of a threshold experience.