For three months each year, you can walk from the USA to Russia across an ice bridge—a frozen path known as the Ice Curtain. In 1963, when the body of a woman is discovered frozen into this icy no-man’s land, the already fragile geopolitical balance between these two countries threatens to collapse. With nuclear tensions intensifying, a veteran FBI agent and an ambitious new female KGB operative are forced into an uneasy alliance to solve the murder — before the ice melts and a global conflict is triggered.