Expedition Leader Paul Rose, environmentalist Philippe Cousteau Jr, maritime archaeologist Dr Lucy Blue and marine biologist and oceanographer Tooni Mahto investigate how the Mediterranean gave rise to one of Europe's first superpowers by diving the remains of a Roman shipwreck. Under the cover of night, they brave the treacherous waters of the Straits of Messina to search for one of the largest predatory sharks in the world - the increasingly threatened, prehistoric six gill shark.