The Silent Service plot
Japan and the United States have been secretly building a nuclear submarine: the Sea Bat. Although the submarine is under the command of the Americans, the Japanese Shiro Kaieda is the captain. He and the 76 crew members staged an accident after which the media reported that they had sunk. In reality, Shiro has a hidden agenda. He loads the submarine with a nuclear missile and disappears into the deep ocean. The United States now sees him as a terrorist and they order the sinking of the Sea Bat. The Japanese send their own submarine, led by Hiroshi Fukamachi, to get ahead of the Americans and find answers.