“Some say the world will end in fire, some say in ice.” Thus Robert Frost warns President Kennedy about the Shadow, before departing on a classified mission on the first nuclear submarine, the USS Nautilus. Past and present collide in this thriller. In the present, on the Nazca Plain in Chile, an old woman has been studying ancient lines in the ground for decades. Now she finally understands their terrifying message. In 480 BC, King Leonidas leads 300 Spartans to Thermopylae to try to delay the massive Persian Army. Known only to the King, they have an even more important mission: to escort and protect a powerful priestess to a mystical gate through which she can travel to help save the world. It’s a mission for which Leonidas will gladly sacrifice his own, and his men’s lives.