Gallifrey, world of the Time Lords. The Doctor returns and claims the vacant presidency. But his behaviour is erratic and his motives mysterious.

The Doctor is made president of the Time Lords. He immediately orders K-9 to lower the planet's defences and has Leela banished to the wilderness.

The Doctor has betrayed his own people and enabled a Vardan invasion of Gallifrey. Leela joins forces with the Outsiders and prepares to strike back against the aliens.

The Sontarans have invaded Gallifrey, seeking to seize the incredible power of the Time Lords. The Doctor's first step is to cut them off from their fleet. But Kelner is helping the enemy…

The Sontarans finally invade the TARDIS itself, seeking the Great Key. The Doctor, however, has other uses for this powerful object…