The journey of the narco-submarine seized off the Galician coast begins in the Amazon jungle, in a clandestine shipyard and with a crew made up of two Ecuadorians and a Galician pilot who was recruited at the last minute.

The submarine goes out into the Atlantic and before reaching the Azores it comes across a storm that causes a breakdown. At the same time, the notice is given that an "unusual" vessel is heading for the European coast.

Coexistence inside the submarine is unsustainable. A first unloading attempt is made in the Strait of Gibraltar, but fails. The boat heads north, to the mouth of the Miño. Meanwhile, the police search for the ship.

After reaching Galician waters, the submersible is chased to prevent the drug from being unloaded. After being intercepted by the Civil Guard, the ship headed for the Aldán estuary. The boat is abandoned and the land pursuit begins.