The Doctor and Sarah encounter Professor Sorenson who plans on transporting anti-matter.

The Doctor and Sarah arrive too late, and a ravenous monster emerges from Zeta Minor.

The Doctor and Sarah continue their efforts to stop the release of deadly anti-matter.

The Doctor realizes not only must he save the universe, but Sorenson, from himself.

After a meeting in space with a group of unseen aliens the Doctor returns to Gallifrey and claims the presidency of the Time Lords. Leela meanwhile tries to work out why he is behaving out of character. At his induction, the Doctor is 'crowned' with a device giving him access to the Matrix. He then arranges for the transduction barriers around Gallifrey to be put out of action by K9. When this is done, his alien 'friends' materialise. They are telepathic invaders called Vardans.

Finding the fourth segment of the Key to Time was simple enough, but holding onto it may be another matter. The Doctor finds himself embroiled in the political games of the planet Tara, where androids complicate the coronation of the planet's rightful Prince.

After a meeting in space with a group of unseen aliens the Doctor returns to Gallifrey and claims the presidency of the Time Lords. Leela meanwhile tries to work out why he is behaving out of character. At his induction, the Doctor is 'crowned' with a device giving him access to the Matrix. He then arranges for the transduction barriers around Gallifrey to be put out of action by K9. When this is done, his alien 'friends' materialise. They are telepathic invaders called Vardans.

The Doctor encounters a dragon.

The Doctor meets evil Mr. Kane.

In 12th century England, infamous thief baron Irongron attracts the interest of Sontaran warrior Linx, who has unwillingly landed on Earth. To repair his ship Linx must travel through time, entering the realm of UNIT and Doctor Who.

Doctor Who gets a glimpse of a Sontaran warrior and quickly travels back in time to Medieval England. While making the trip the Doctor realizes noise in the compartment is reporter Sarah Jane Smith who due to circumstance, becomes his companion.

The captured UNIT scientists remain in captivity when the Doctor and Sarah arrive in Medieval England. To make matters worse, Sontaran Warrior Lynx requires scientific expertise to repair his ship and thus forms an alliance with chief Irongron.

The Doctor hopes to rescue the scientists but must first face off against Sontaran Warrior Lynx and chief Irongron, both of whom are intent on stopping him. A primitive weapon however, may be the Doctor's only effective strike against the sinister allies.

Still following the Black Guardian's orders, Turlough sabotages the TARDIS.