In Summer 2005, a mysterious submarine is discovered off the coast of Italy at 120 metres deep. For Lorenzo del Veneziano, an underwater marine archeologist, it is an amazing sight. The submarine is intact! It stands almost vertically at the bottom of the sea, it's hull stuck in the sediment. What is the story of this ship, why is it here? By uncovering the mystery of its origins we will retrace the incredible story of U-455, a German warship that fought every marine battle against the Allies, from the Baltic Sea, to the Atlantic and then finally the Mediterranean where it now rests. An extraordinary underwater adventure and an ambitious historical investigation.