A woman (Adams) is found drifting in an open boat, with little or no memory of what happened to her. Turns out she was on a diving cruise, when the boat ran aground on a wreck just off a remote island. Going ashore they find an apparently-deserted villa - only to eventually locate its sole inhabitant, a former SS officer (Cushing), who reveals that they have just unleased the remnants of a Nazi experiment. The aim was to create the 'ultimate soldier' - unstoppable killing machines that need no weapons - but that controlling them proved impossible. A platoon were sent away shortly before the fall of the Third Reich, and after waiting for orders that never came, the officer scuttled the boat, and took up residence on the island so he could keep an eye on his wards. Unfortunately, the unexpected arrival of the tourists has awakened the soldiers from their decades-long slumber, and just as at the end of the war, they're not too picky about who they kill.
It's a grand idea, and the execution of the zombies is also atmospheric. With their peroxide-white hair and welder's glasses, they look like a European industrial band as they rise out of the water, and simply drown their victims with a minimum of fuss. However, despite this, and the immaculate presence of Cushing, this is ploddingly-paced, and the frequent shots of the zombie plouging through the water are nowhere near as interesting as the makers think. The plot dangles fragments randomly e.g. the strange orange light in which the ship is bathed near the beginning, or the larger boat which runs into it during the middle of the night. Neither are ever referenced again. Cushing and the other genre icon involved, collect their cheques and vanish without fanfare, leaving us to the much less interesting cast members, who stumble around making poor decisions, even managing to let the most serviceable boat on the island sail off without any of them on it. I think I started cheering for the Nazi zombies at that point.