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.

Andrew Craig and his team head back to the SS Gairsoppa to recover the silver ingots, but a personal tragedy arises necessitating the replacement of a key team member and then bad weather forces Andrew to change course for another wreck, the SS Mantola.

Odyssey have just one more month of summer weather before they will be forced to shut down operations for the year. Aboard the Seabed Worker, a deepwater recovery vessel, Andrew Craig and his team work furiously to salvage a fortune in silver from the SS Gairsoppa. They think there may be up to 200 tonnes of bullion stashed in her holds.