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.

With his wife Elizabeth on life support after a boating accident, Hawaiian land baron Matt King takes his daughters on a trip from Oahu to Kauai to confront a young real estate broker, who was having an affair with Elizabeth before her misfortune.

When mankind beams a radio signal into space, a reply comes from ‘Planet G’, in the form of several alien crafts that splash down in the waters off Hawaii. Lieutenant Alex Hopper is a weapons officer assigned to the USS John Paul Jones, part of an international naval coalition which becomes the world's last hope for survival as they engage the hostile alien force of unimaginable strength. While taking on the invaders, Hopper must also try to live up to the potential that his brother, and his fiancée's father—an Admiral—expect of him.