Ordered across the Pacific Deeps a Virginia Class attack sub the USS Obama, captained by Russell Grant has orders to proceed towards North Korea and to monitor the rogue nation from the nearby Yellow Sea.

Unfortunately for the Obama a killer is loose within the sub and it becomes a race against time to stop either a madman or a deep plant put in place by the North Koreans. Grant orders Jennifer Hobbs, a newbie within the ranks but an ex-homicide investigator to look into the killings and she is soon joined by two NCIS specialists flown in from the mainland.

However when one of the agents is murdered in the same fashion, Hobbs must step up her investigation and unearth the killer before the whole mission is scuppered.

With the sub' hovering at DEFCON 1, can Hobbs succeed and help prevent a devastating nuclear conflagration?