 Julia may be 10 years old and lives near the Czechoslovakian border. For some time she had become mute, but she lives a rather normal life, going to school and playing with other kids. One day the other kids urge her to go into the tunnels at the border. These tunnels are military remnants from the Second World War, which the Czechoslovakian authorities have no doubt done their best to block effectively. Nevertheless, Julia comes out on the Czechoslovakian side, where a team of soldiers are building a high and solid steel fence to prevent other kinds of escape. Julia and a middle-aged soldier become friends, and he helps her to avoid being detected by the others. For many weeks she goes forth and back between the two countries. The man also promises to change the place of the fence so that her tunnel will not be closed. He knows too much about the leading officer, so the latter would never dare to protest. But whatever the reason, one day Julia finds the fence at a place she cannot cross. She has lost her best friend.