Auf hoher See

A sailor is murdered on a freighter of the Swiss merchant navy. Aurélie Mercier, a former inspector who has been transferred to the city administration, travels to Cape Town to bring back the suspect Florian. But he protests his innocence and says he is looking for his girlfriend Julia.

The cargo ship prepares to weigh anchor. Aurélie decides, following her instinct, to stay on board with Florian. On the high seas, the inspector searches for the real murderer, but an evasive captain and a hostile crew make her work difficult.

An unexpected witness gives the investigation a new twist. A mysterious box is to be transferred to a ship in distress. For Aurélie, every answer leads to more questions. She seems to be on the trail of the truth when tragedy is announced.

Aurélie realizes that not only has a murder been committed on the freighter, but that prohibited goods are also being transported. She no longer knows who she can trust. In a confrontation, Aurélie takes up arms and brings to light the truth about what happened to Julia.