 The mission is successful until the submarine's second-in-command, the president's son Linus Clark makes a fatal error, and the submarine collides with a sonar array from a Chinese ship that is searching for them.The crew is imprisoned and tortured while the Chinese begin to strip the captured submarine for its secrets.Desperately, Arnold Morgan, the National Security Advisor, plans a mission to get the crew back, safeguard the sub's secrets, and punish the Chinese.