Summer 1941 - Hitler launches his surprise assault on the Soviet Union. As German Panzers drive deep into the heart of Russia, the Red Army is desperate for help that can only be delivered through convoys of Allied merchant ships sent through the bitter Arctic. But appalling weather and deadly cold are not the only dangers awaiting the crew of the little escort ship HMS Protea. They must run the gauntlet of attacks by German aircraft and surface raiders, as well as the wolfpacks of U-boats waiting for them amid the ice.

Following on from Sea of Wolves, the Wolves in Winter plots the lives of those caught up on both sides. Jürgen Bortfeldt, the music-loving commander of U-133, struggling to control the tensions amongst his divided officers. Jan Pedersen, a member of the Norwegian resistance, fighting the enemy occupying his country in whatever way he can. And Vera Baldwin, the skilled codebreaker at Britain's Bletchley Park and the unseen hand guiding the Protea and her convoys through the dangers crowding around them.

Triumph and tragedy await them all in a battle fought across the roof of the world.