In the cold, dark waters off North Korea a U.S. Navy fast attack submarine meets with a mysterious disaster - it's attacked and nearly sunk by an ominous stealth submarine resulting in the deaths of the Executive Officer and the Engineering Officer. The sub's captain, Commander Burt Habley, faces a court-martial by a Naval Board of Inquiry. He's rescued from this fate when he's chosen to lead a top secret mission back to tap a North Korean underwater communications cable. Habley must protect his boat and crew from this phantom submarine while completing a successful mission. His instincts tell him they're being followed and he begins to navigate the sub away from the original mission and into open waters drawing the phantom sub away from the U.S. fleet. This puts him at odds with his new by-the-book Executive Officer who eventually, with the help of the special missions team, takes command of the submarine and navigates back on course just as they are attacked again. Validated, Habley and his crew come together to defeat this dangerous enemy before they can destroy them or the fleet.