In 2039, rising seas push humanity to the brink, and the Fleet of Fog, powerful foes shaped like old wartime vessels, cuts off travel and communication between regions. Ordinary weapons fail against them. Gunzou Chihaya captains Iona, the Fog submarine I-401 that stands on humanity's side, and he and his crew, Blue Steel, are sent by the Japanese government to carry the Vibration Torpedo Warhead across hostile waters to the United States so it can be mass produced. They hope for a peaceful end to the conflict. The film is a sci-fi action compilation of the television series with newly added story sequences.