A dangerous game of hide and seek begins inside the TARDIS when the Sontarans get in.
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 taken control of the Capital on Gallifrey and intend to use the power of the Time Lords to rampage through all of time.
As the Vardans finally fully materialise on Gallifrey, the Doctor prepares to spring his trap. But does a more deadly alien force lie behind the Vardans?
