Computer-generated imagery strips the water away from the South China Sea, exposing wrecks that satellite and sonar surveys have mapped but never fully explained. The centerpiece is the resting place of the largest battleship ever built, its hull broken apart on the seabed after a doomed mission near the end of the Second World War. Alongside it, the film pieces together a shipwreck mystery historians have argued over for more than 700 years, using sonar scans, dive footage, and interviews with maritime archaeologists and naval historians to reconstruct what happened and why. The digital drainage technique lets the film show reef systems, sunken cargo, and hull damage in a single continuous image rather than scattered dive clips, then rebuilds the ships and battles above the empty seabed with CGI. Between the battleship and the older wreck, the episode covers centuries of trade routes and naval conflict that used these waters, treating each wreck as physical evidence for a specific historical argument rather than a general tour of the ocean floor.