It is based on the true story of the Polish World War II submarine ORP Orzeł. Since the real Orzeł was sunk in the war, to assure authenticity her role was played by her sister ship, the ORP Sęp. The film was entered into the 1st Moscow International Film Festival. Basically the story is freely based on the so-called 'Tallinn-episode' of the Polish submarine 'Orzel', which in Sep. 1939 entered the harbour of then still neutral Estonia to leave her commanding officer with symptoms of illness. The Estonian authorities tried to intern the sub under the pressure from the Nazi-Germany, but the 'Orzel' escaped.