Watch The Silent Service

The floating dock Southern Cross, which is carrying the Yamato, begins to sink under the attack by the U.S. forces. Steiger, commander of the U.S. Pacific Fleet, is eager to sink the Yamato, which escapes just in time before it sinks. The Tatsunami, that was put at risk to escort the Yamato, begins to sink.

Kaieda appears at the meeting. The alliance negotiations between Japan and the independent nation Yamato are reported to the world. At the conclusion of the meeting, President Bennett identifies the Yamato as a terrorist organization and orders its destruction. Escorted by the Tatsunami, the Yamato attempts to leave Tokyo Bay.

After the battle with the U.S. Third Fleet, Kaieda arrives at Tokyo Bay to conclude an alliance with Japan. The Japanese government announces to the public a series of events that began with the top-secret Seabat Project. Ichiya, a news anchor, is present at the press conference.

A Japan-U.S. summit meeting is held, but neither country concedes to the other's claims. Prime Minister Takegami continues with the negotiations, hoping to avoid war. Meanwhile, the U.S. Third Fleet launches an anti-submarine missile at the 2nd Maritime Self-Defense Force convoy led by Commander Numata, which has been dispatched to escort the Seabat. Numata tries to maintain a defensive posture.

Kaieda finally begins to combat the U.S. forces. Three nuclear submarines of the Seventh Fleet close in on the Seabat. Meanwhile, the Japanese government is preparing for a summit meeting with U.S. President Bennett. Chief Cabinet Secretary Wataru Unabara moves in to coordinate the will of the cabinet.

Fukamachi's diesel ship Tatsunami arrives in the area, where the operation is in a standstill after Kaieda's declaration. Fukamachi boards the Seabat to try to stop Kaieda, and he hears about Kaieda's true intentions. Meanwhile, the Japanese government holds an emergency meeting to discuss the fate of the Seabat Project and Kaieda's treatment.

The state-of-the-art nuclear submarine Seabat, which was hijacked by Kaieda, surfaces in front of the U.S. Seventh Fleet, which has assembled to sink the Seabat as it is considered a terrorist threat. As the Seventh Fleet is about to launch a simultaneous attack, Kaieda loads a torpedo in an attempt to intercept the submarine. He declares that the warheads are not conventional - in other words, nuclear - and makes an even more startling declaration.

The Maritime Self-Defense Force submarine Yamanami collides with and crushes a U.S. nuclear submarine in the waters near Japan. Shocked by reports that all 76 crew members, including the CO, Shiro Kaieda, were killed, Hiroshi Fukamachi, CO of the MSDF diesel submarine Tatsunami, becomes suspicious of the accident and analyzes the data recorded at the time of the collision, which reveals that Kaieda and his crew had escaped just before the accident. Fukamachi has a history with Kaieda due to a past maritime accident.