Treasure hunting trio Sidney, Ali and Gemma are back in what might be their most challenging quest yet. When their expertise is requested by an unlikely source, they embark on a clandestine hunt to find one of the most significant shipwrecks in US Naval history. As ever, they are not the only ones searching for the prize, and it seems it is more than just history on the line. With international security at stake and a two hundred year old ship with an explosive secret, have the team taken on more than they can handle this time?.