After losing her mum Katie, A adolescent girl, can't snap out of her depression. Katie has lost interest in her close friends school, and swaying. That varies at summer time when she's asked to monkeysit Gibby. Taking good care of this monkey changes her life . The happy-go-lucky personality of gibby renews the zest for life of Katie. Gibby helps her with gymnastics, hammering friendships (including getting a possible boyfriend) and overcoming her nemesis, an average girl who's going to be at Katie in any respect.