A boy learns he is a war orphan and discovers his hair has turned green. Other war orphans tell him he must remind people that war is bad for children.
A boy with no hair refuses to say his name. Dr. Evans (Robert Ryan) shares his lunch with him and asks about his hair. Peter Fry (Dean Stockwell) tells his story even though he does not expect him to believe him.
A telegram says that his parents are war casualties, and Peter goes to various relatives. Gramp Fry (Pat O'Brien) sings for the King (Walter Catlett). Peter goes to live with Gramp. Peter breaks a vase on purpose, but Gramp does not get angry. So Peter decides he will stay there. Gramp asks Peter if he is afraid of being alone or in the dark, but Peter is not afraid.
In town Gramp introduces his grandson to people. Peter goes to school and has a pretty teacher, Miss Brand (Barbara Hale). Peter gets a bicycle and a job delivering groceries. Gramp drives Peter and the boys to collect clothes for war orphans. A boy calls Peter a war orphan, and they fight. Gramp tells Peter that his parents are dead.
At the grocery store Peter hears a conversation about ending war. Gramp says that Peter will have a surprise. The next day Peter washes his hair and finds that it is green. Gramp says that it is for something that he is going to do. Gramp takes Peter to Dr. Knudson (Samuel S. Hinds), who finds nothing wrong with him.
Peter walks to school and tells men that he did not dye his hair. Kids are afraid it is contagious. Miss Brand asks how many students have hair that is black, brown, blonde, green, and red. At home Peter rips the letter from his father. He goes into the woods and cries. He sees war orphans that were on the posters, and they explain that his green hair is to remind people that war is bad for children. Peter goes and tells people.
Davis (Regis Toomey) complains that people are buying less milk. Gramp and Dr. Knudson suggest he cut off his hair, but Peter refuses. Peter goes back to the woods and runs from boys with scissors. He helps a boy find his glasses and then escapes from him on his bike. Gramp takes Peter to the barber, who shaves off his hair. Peter does not eat or talk. Gramp feels ashamed.
Peter leaves at night and tells Dr. Evans that that was last night. Dr. Evans says he does not believe it. Peter sees that Gramp, Dr. Knudson, and Miss Brand are there. Gramp reads his father's letter to Peter, which asks him not to forget and to remind people. Peter keeps the letter and tells Dr. Evans that his hair will grow back green. Dr. Evans and Dr. Knudson believe in Peter. At home Gramp and Peter sing.
Writer Ben Barzman and director Joseph Losey were blacklisted
after this film was made. This fantasy explores prejudice for
anyone who is different while conveying a message after a horrific
war that humans must change their nature and stop having wars,
or there will be no humans left to change.