Moscow 1967. The Doctor and Ace have arrived behind the Iron Curtain, and the Soviet Union is seeking a new weapon that will give it mastery in the Cold War.

What is the secret of the Martian relics? As the legendary War Lord Sezhyr returns to life, the Doctor is faced with some of his oldest and deadliest enemies.

The fate of Earth – and the future of Ace – are now intertwined...