When Captain Lannec finally owns his own freighter, it marks the beginning of the end. He has received the necessary guarantee from the Pitards, the family of his wife Mathilde. Therefore, he cannot forbid Mathilde from participating in the maiden voyage of the "Tonnere-de-Dieu," the "Thunderstorm." In the suffocating confines of the ship, jealousy and mistrust grow - both between the couple and among the crew. A mysterious, ominous letter and an approaching storm also promise nothing good.