Teenage David Witton lives in foster care following his father's departure from home when he was small and his mother's breakdown, and attends a rowdy remedial class. He is happiest communing with nature, nude swimming, and birdwatching with his only friend, fellow loner Fred. Though he impresses his teacher with his knowledge of nature, a school trip to a nature reserve ends in disaster when David has to kill an injured deer. Following the death of his precocious foster sister and the burning down of Fred's hut by a mob who learn that he is an ex-paedophile, David sets free his abusive foster father's captive birds and sets off in search of his real father.