Residents of a Swedish village told the loving couple Vilma Persson and Simon Cureau that somewhere in the remote Lake Vittangi-Jarvi, a German transport plane that fell at the end of the war rests at the bottom. Vilma and Simon, experienced divers, were inspired by the idea of going down to the bottom of the lake and exploring the ship that had fallen from the sky. They were not even puzzled by the fact that it was winter and the lake was covered with a thick layer of ice. Simon and Wilma plunged into the cold waters through the wormwood. However, they never made it to the top... Was it an accident during a dive in extreme conditions? Investigator Anna-Maria Mella and prosecutor Rebekka Martinsson think differently. They came across traces indicating that someone had prevented the scuba divers from surfacing. But Wilma and Simon had no enemies? Or did they touch someone's secret?