The world's oceans are no longer safe. Mysterious alien invaders have conquered two-thirds of the earth's surface-its oceans-and now nations are reeling from the savage attacks that have struck every shore. Los Angeles and Washington D.C. are war zones.

The survival of the United States depends on heroes.

Among them are a grizzled Army veteran who pilots his ASHUR in defense of the nation's capital, a brilliant analyst who works feverishly to unravel the secrets of the invaders, and the bold and daring officers of the US Navy, battered from below yet seeking to salvage victory from the jaws of defeat.

Yet some of the unlikeliest of heroes are the people who emerge from the shadows of everyday life to fight for their very survival as the alien incursion carves deeper into the continental coastlines.

Fighting in the currents is hard enough. Fighting the RIPTIDES is even harder...