Tony Robinson accompanies James Cameron, the Oscar-winning writer, director and producer of the blockbuster film Titanic (1997), on a poignant farewell to the most spectacular shipwreck in history. Nearly 10 years after Cameron's first visit to the wreck, this is his last.

In July 2009, amateur metal detecting enthusiast Terry Herbert uncovered the largest Anglo Saxon treasure hoard ever found in Britain. Just below the surface of a field near Lichfield, Staffordshire, he unearthed over 200 pieces of jewelled gold and silver treasure, buried, lost and forgotten for over a millennium. Archaeologists later excavated a further 1,400 items. The unprecedented find of Anglo Saxon gold mesmerised archaeologists and historians, making headlines around the world.

Experts in code writing and breaking tell tales of heroic risks and cat-and-mouse secrecy, where science meets deadly adventure and everyone from queens to soldiers to everyday citizens can pay the price.

It's a treasure hunter's dream come true? buried gold worth millions, found just inches below the surface. In the past 30 years, three million-dollar treasure hoards were discovered: the Staffordshire hoard and Hoxne hoard in England, and the Saddle Ridge hoard in California. Each was found completely by accident, and changed the lives of the finders forever. Now, experts examine the precious treasures and try to piece together the mysterious and fascinating stories behind them.