More than a million tonnes of unexploded bombs, mines, and shells from the Second World War still sit on the floor of the North Sea and the Baltic, dumped there in the chaos after 1945 when nobody had a better plan for getting rid of them. This film follows the divers, naval ordnance disposal teams, and engineers who now have to deal with that legacy, decades after the fact and with the casings rusting through. Cameras go underwater with bomb disposal crews as they locate, identify, and defuse corroding munitions on the seabed, while fishermen describe hauling up shells in their nets and marine biologists explain how leaking TNT and heavy metals are seeping into the water and the food chain. Engineers demonstrate the robots and specialized ships being developed to find and remove ordnance faster than divers can manage alone. The film lays out the scale of the cleanup problem plainly: nobody knows exactly how much is down there, disposal is slow and dangerous, and the munitions are only getting less stable with time.