Jimmy's father is away, fighting in the navy, and Jimmy feels responsible for looking after the house and his mum in his father's absence. One day, Jimmy goes to the cinema and loses track of time. When he leaves, it's dark - then the sirens start. It's a bombing raid! A warden forces Jimmy into a shelter and won't let him out until the morning. When he finally gets home, he discovers there's no home to go to. It's been bombed out and his family are nowhere to be found. How will Jimmy survive alone of the dangerous streets of London? And will he ever find his mum and sister?