Survivors of a planetary explosion find the lost gene banks of their ruined civilization and its guardians ruled by the ship's computer. With Tom Baker.

The Doctor must get into the Citadel to rescue Ida's father and save the race bank, but the way is guarded by dragons

Even if they acquire the vital cylinders, escape seems impossible with the spaceship trapped at the planet's core without fuel.

After returning to Gallifrey to claim his position as president, the Doctor strangely appears to turn traitor.

A Medusa lies in wait in the maze.

The White Robots drag Jamie and Zoe away.

The TARDIS lands on Varos.

Mistaken for rebels, the Doctor and Peri learn that Sil is making a bid to rule Varos.

The travelers work to overload the computer.

Ice Warriors on the moon; the first appearance of T Mat; the Doctor visits a rocket museum.

The Doctor orders Leela expelled to the wastes of outer Gallifrey.

The Doctor sides with aliens.

The Doctor and Leela separately fight the invaders.

The Time Lords appear helpless in the face of the Sontaran onslaught.

Hope grows dim as the Sontarans invade the Tardis itself.

The Doctor and Romana set out to collect the six segments of the [sic]

The Doctor finds the first segment, but he and Romana are threatened by trickery.

The Doctor, Romana and K9 are caught between deadly weapons and savage beasts.