In the treacherous waters of the South China Sea, a father-son team of explorer-divers embarks on a perilous mission to locate the final resting place of two American submarines that vanished during the Second World War. Guided by the haunting testimony of a lone survivor and the expertise of a global network of contacts, the duo navigates the dangerous depths to uncover the truth behind the mysterious sinking of the USS Robalo and the USS Flier. As they descend into the abyss, they confront the harsh realities of deep-sea exploration, where every second counts and the line between discovery and disaster is razor-thin.