Beneath the dark waters of the Gulf of Mexico, an ancient threat stirs to life. When an ultra-advanced German U-boat — long thought to be a myth — resurfaces in the Gulf, Michael Gannon and his Water Horse crew are thrust into a deadly race against time. The Sleeping Wolf wasn't just another submarine; it was designed to carry destruction straight into the heart of America. Eighty years after World War II, new enemies plan to finish the mission. From the sun-drenched shores of the Florida Keys to the treacherous depths of the Mississippi Delta, Gannon’s team must track down the X-601 before it falls into the hands of a ruthless modern enemy. Armed with cutting-edge technology and an ironclad bond forged at sea, they’ll battle secrets, underwater death traps, and betrayals lurking just beneath the surface. But the deeper they go, the more they realize