Andrew Craig and his team set out on the RV Explorer, Odyssey Marine’s flagship vessel, to try to locate the SS Gairsoppa, a steamer sunk by a German submarine in the darkest days of World War II. Hidden somewhere inside the wreck is silver bullion said to be worth as much as £120 million. After weeks spent carefully surveying the seabed, the team locate the wreck some 300 miles south west of Galway Bay, lying 4,700 metres below the surface of the North Atlantic, a depth from which no treasure has ever been recovered before. The team soon realise that they will need tools more powerful than those they have on board the Explorer. They charter a deep-water excavation vessel, the Seabed Worker, to tackle the challenge, and Andrew devises a plan to deconstruct the steel wreck with specialised equipment. But the team soon learn that there are good reasons why no-one has ever recovered loot from this depth before. They battle unpredictable weather and equipment malfunctions, as well as the ever-present dangers and uncertainties of working nearly five kilometres beneath the sea. Andrew and his crew succeed in confirming that there is a fortune in silver hidden inside the wreck. But after 28 days, they still cannot raise the haul and are forced to suspend their quest and return to port. Will the SS Gairsoppa’s treasure remain on the seabed for ever?