THE HIDDEN THREAT serves as an introduction to the submarine and the life the submariner leads. Riding the razor thin edge of mutually assured destruction, U.S. and Russian nuclear submarine forces wage a secret war. It's a deadly game of cat and mouse, hidden from the scrutiny of the outside world. No satellite or laser imaging system can track them. Their own governments never know exactly where they are. And once on patrol, the "silent service" is accountable to no one but themselves and their singular mission. These are the massive SSBN "Boomers" and their SSN class "Hunter-Killer" shadows-—missile and fast attack platforms capable of unleashing unimaginable devastation. When the launch sequence begins, only a precarious fail safe system or an enemy's torpedo can stop them. Shrouded in secrecy, few have ever understood the risks of this strategic defense... until now.