In September 1939, the United Kingdom declares war on Nazi Germany, and children are evacuated from London to the countryside for their safety.

Tom Oakley, an elderly widower living alone in the rural village of Little Weirwold in Devon, is forced to look after one of the evacuees, William "Willie" Beech.

It is obvious, however, that Mrs Beech has been made much more uneasy by the Blitz, and after an argument sparked by her discovery of the absence of the belt, she sends Willie to his room for the night.

The next day, Mrs Beech seems better after suffering a mental breakdown, but when Willie presents her with gifts that the locals from Little Weirwold had given him, and tells her about some of his friends, she accuses him of stealing and is angry he had been interacting with girls and Jews.

She finally pummels him and eventually locks him in the cupboard under the stairs, accusing him of blasphemy after he tells her that "Jesus was a Jew".

Tom visits Willie in the hospital and meets Dr. Stelton, a child psychiatrist who works with a children's home in Sussex.

Eventually, Stelton and some social workers come to Tom's house with the news that Willie's mother has died by suicide.

Unfortunately, Willie's newfound happiness is cut short when Zach receives a phone call from his mother, saying that London's East End was bombed while his father was there.

In the film's final scene, Willie rides the bicycle down the long hill and stops just in front of an impressed Tom, whom he addresses as "Dad" for the first time.