Based on a true story of Polish submarine "Orzel" (The Eagle): September 1939, "Orzel" is coming to Estonian neutral harbor in Tallin. Under pressure from Germany Estonians have intern the ship. Commander Grabinski decides to escape to England through the Baltic Sea, without any maps that has been confiscated and with only small amount of fuel on board.
Diver Antoni Barnat is falsely accused of causing an accident underwater that almost led to his fellow diver's death. Interestingly enough, they are both in love with the same girl, Teresa.
A ship crew fight over a deceased captain's notebook, believing that it contains clues to find a treasure.
