The legendary detective Ture Sventon has not solved a case in twenty years when his old arch-enemy Vessla suddenly escapes from prison. Ture suspects that Vessla has a secret plan, linked to the mysterious Bermuda Triangle.
Ture goes to Rimboanstalten to investigate Ville Vessla's disappearance. At the same time, Vessla wakes up on a ship together with a mysterious company that is in search of the forces that hide at the bottom of the Bermuda Triangle.
Ture is on the run from prison. With the police on his heels, he finds a new track that leads to a mental hospital in London. There, Ture meets a pilot who can recreate valuable memories from when his plane crashed in the Bermuda Triangle.
Ture realizes that the only one who can tell about the origin of the pyramid is Professor Omar. Ture and the children fly to Egypt where Omar is working on an excavation in a mysterious burial chamber, but once they arrive, Omar is gone.