The cataclysm that began with coordinated reactionary coups in South Africa and Germany caught America completely unprepared. Overnight, new enemies have emerged and joined forces to attack U.S. and European shipping lanes, setting off a global conflagration raging in deadly earnest. And this time the devastating weapons of choice used by the Berlin-Boer Axis will be tactical nuclear weapons.

The enemy boat Voortrekker prowls beneath the ocean's surface, carrying more onboard firepower than that of many of the world's nations. A deep-diving state-of-the-art German ceramic-hulled submarine, Voortrekker has the ability to evade all Allied sensors and can fire torpedoes from any angle, further masking its location. There is only one weapon in America's arsenal that can match the silent killer: the crippled sub USS Challenger, presently in dry dock in Connecticut. It will take three weeks to get the U.S. ceramic-hulled sub back into fighting shape and by then it will be too late. The Axis Powers have already proven they can get past America's frontline seapower defenses. And the Voortrekker is moving into position for the ultimate strike.

Brash, brilliant, and battle-tested, Captain Jeffrey Fuller is the driven naval officer who must oversee the miracle that will put Challenger back into action in an improbable forty-eight hours. Then Fuller himself will have to do the impossible, piloting his damaged sub toward a life-and-death confrontation with the Axis leviathan. Fuller has already faced the Voortrekker's ruthless, ingenious commander head-to-head - and unlike so many others, he survived. But this time the fight will take place in waters far too deep for a normal sub to withstand - in the terrifying blackness at the ultimate submarine's crush depth. And this time the prize will be America.