Hamburg harbour, early 20th century. Gus, a young man, passionately in love with Ellena, the daughter of a merchant captain, follows her on board the cargo sailing vessel named Lais, hiding himself as a stowaway.
The ship has already embarked on its journey when the young lovers discover that it carries a secret military cargo, fated for an unknown destination. They soon learn that the real boss on board is not Ellena’s father but the sinister military agent Laufer, a brute with no qualms about having anybody thrown overboard who shows undue interest in the cargo and does not follow his orders to the letter.
Gus thus has to remain hidden in the belly of the ship, an endless labyrinth of corridors and secret passageways. The journey becomes a trying ordeal enlivened only by the clandestine visits of his beloved and the company of some of the seamen who discover his presence on board and befriend him.
Slowly, Gus becomes aware of the sailors’ rising fear of the unknown cargo. As Ellena’s visits become fewer and rumours hint of an alleged alliance with Laufer, Gus struggles increasingly to keep his mind from unravelling, while madness and paranoia steadily rise around him.
After a heavy storm, Ellena is found missing. The crew believes Laufer is responsible for Ellena’s disappearance. Panic spreads on board. Set on finding Ellena and hell bent on taking revenge on Laufer, Gus becomes the leader of a mutiny...