Sandy (Barbara Hershey), Dan (Bruce Davison) and Peter (Richard Thomas) are three affluent, spoiled teens spending a lazy summer on Fire Island, N.Y. Both boys pepper Sandy with sexual advances, which she clearly relishes. Into their tight triangle comes chubby and naive Rhoda (Catherine Burns). Like the injured seagull Sandy both nurtures and tortures, Rhoda becomes a figure of sport, teased and humiliated by the group. Sandy's cruelty and influence brings the summer to a shocking climax.