United States Navy officer and Medal of Honor winner Dan Lenson’s mission is to observe an international military exercise involving the navies of South Korea, Japan, Australia, and America. It should be routine duty for Dan, but old alliances are unraveling as North Korea threatens the U.S., and China expands its influence.

Now, acting as both adviser and adversary to a ruthless South Korean task-force commander, Dan must stop a wolfpack of unidentified submarines—armed with nuclear weapons—which are trying to elude Allied surveillance and penetrate the Sea of Japan. Is it the start of an invasion…or an elaborate feint, to divert attention from a devastating attack?

Battling faulty weapons, a complacent Washington establishment, and a fierce typhoon season at sea, it’s time for Dan to act on his own—even if doing so means the end of his career, the lives of his observers, and the risk of nuclear war.