Group psychopathology--unconvincingly rendered--within a quintet of hip, brilliant, well-fed, emotionally needy N.Y.C. teenagers. They're the above-it-all, intense in-crowd in the junior class at the posh Demaret School: Peter, living alone in his Upper West Side apartment now that his faddish parents have gone native in Taos; cool, gorgeous Wendy, who has a religious-fanatic father, ""a millionaire redneck""; tall, plain Elizabeth, who has a rejecting mother; and ""Crunch,"" whose smarmy parents (""such Babbitts"") have decided they can't afford to pay for his college education. This foursome smokes dope, pulls ""capers"" (minor thefts, con-jobs), swears do-or-die loyalty to the group. After initial reluctance, they allow scholarship student Vinnie Santini--a math genius from Staten Island--into their games and rituals. Meanwhile, Crunch yearns for Elizabeth's pretty cousin; Peter secretly seduces Crunch's younger sister Gina; everyone lusts after Wendy. (Her ""kiss had pulled the scab off Peter's heart."") Then Elizabeth violates the group-rules--by going off on her own in an impulsive scheme to help a disturbed little boy found wandering on the street. So Wendy punishes her--and regains power--by blithely treating the boys to some group-sex, the sight of which awakens Elizabeth to the amorality and petty pathology of the group's doings. (""What's the next caper, if we insist nothing happened? We could murder a person and shrug it off."") But this change-of-heart comes too late to avert calamity: when the group finds out about Peter's affair with Gina (an even more flagrant violation), Wendy will restore order. . . by pushing the boys over the edge into a warped revenge-killing (which has been heavily foreshadowed throughout). Bach, author of several far more successful urban/problem YA novels, never quite captures the dynamics of teenage group-obsession (a very real phenomenon); the individual kids' motivations are implausible, crudely sketched; the parents are cartoons; the pretentious Peter Pan allusions hardly help. And, despite lots of aggressively smart, New York-y dialogue, this is finally a thin, contrived psycho-study, most often merely unpleasant.