While spending the summer on Fire Island, Peter and Dan, two adolescent boys from upper-middle-class families, meet Sandy, a young girl who has found a wounded seagull on the beach. After the boys remove a fishhook from the bird's throat, the three youngsters become fast friends and spend all their time together, swimming, boating, smoking marijuana and cautiously experimenting with their awakening sexual impulses during visits to a movie house on the mainland.