After the German occupation of Czechoslovakia in 1939 the Czech pilot Captain Černý, who intends joining the foreign army, says farewell to his wife and small son. He plays young Jeník his favourite lullaby on the piano for the last time. After the end of the War in the spring of 1945 he now returns home as a colonel. From the caretaker he hears the tragic news of the death of his wife and the disappearance of his son. With the help of an organization searching for missing persons and the Soviet officer Pavlov, he starts looking for Jenda in childrens' reception camps. After much disappointment, a coincidence leads him to the German teacher Mrs Weber. She first states unconvincingly that the boy had died. Then Pavlov notices a birthmark on the hand of a boy mending his bicycle in front of the house. Černý plays the lullaby on the piano, the boy runs in and throws himself into his father's arms.
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