The TARDIS falls through a CVE into E-Space and arrives on the planet Alzarius. There the inhabitants of a crashed Starliner and a group of young rebels called the Outlers, led by a boy named Varsh and including his brother Adric, are being terrorised by a race of Marshmen who emerge from the marshes at a time known as Mistfall.

The Doctor discovers that the Starliner's inhabitants are not the descendants of its original crew, as has been claimed by their leaders the Deciders, but evolved Marshmen. With the Time Lord's help and encouragement, the Starliner is repaired and able to leave the planet.

The Doctor, Romana, K9 and Adric - an Outler from Alzarius who has stowed away aboard the TARDIS - arrive on a planet where the native villagers live in fear of 'the Wasting' and of three Lords named Zargo, Camilla and Aukon who rule from an imposing Tower. The Lords are soon revealed to be vampire servants of the last of the Great Vampires, a race referred to in Time Lord mythology.

The Great Vampire is about to be revived from its resting place beneath the Tower - in fact the spaceship in which the Lords, in their original human forms, came to E-Space - but the Doctor launches one of the ship's three shuttle craft and it pierces the heart of the creature, killing it. The Lords, deprived of their master, crumble to dust.

The TARDIS is hijacked in the vortex by a time sensitive Tharil named Biroc, and brought to a strange white void. Biroc wants to free the others of his race who are being transported in a slave ship, captained by Rorvik, which is also trapped in the void. The only other thing present in the void is an ancient gateway leading to a decrepit banqueting hall.

This is the domain of the Tharils, who in a previous time were cruel masters to their human slaves but have now repented. The humans built the Gundan robots to kill the Tharils, and this led to the latter race's downfall.

Rorvik tries to break through the gateway, and thereby gain access to N-Space, by blasting it with his engines. The blast is simply reflected back, however, destroying the ship and freeing its prisoners.

Romana and K9 elect to remain in E-Space to help liberate the remainder of the Tharil race, while the TARDIS - now occupied only by the Doctor and Adric - is able to return to N-Space.

Deep space, an unknown time - on course for Gallifrey, the TARDIS passes through a strange disruption. When they materialise, the scanner shows the Time Lord homeworld... but the travellers have passed into the negative pocket universe of E-Space and are in fact on the planet Alzarius, where evolution works very differently...

Still trapped in negative E-Space, the TARDIS lands on an unnamed world to find a society sliding back into feudalism. What is the secret of the Three Who Rule? And what ancient enemy of the Time Lords is stirring again on this world...?

Still trapped in negative E-Space, the TARDIS lands on an unnamed world to find a society sliding back into feudalism. What is the secret of the Three Who Rule? And what ancient enemy of the Time Lords is stirring again on this world...?

Still trapped in negative E-Space, the TARDIS lands on an unnamed world to find a society sliding back into feudalism. What is the secret of the Three Who Rule? And what ancient enemy of the Time Lords is stirring again on this world...?

Still trapped in negative E-Space, the TARDIS lands on an unnamed world to find a society sliding back into feudalism. What is the secret of the Three Who Rule? And what ancient enemy of the Time Lords is stirring again on this world...?

Nowhere, literally - the Zero Point between the positive and negative universes. The TARDIS materialises in a white void, but the travellers are not alone. A stone gateway, filled with ageing warrior robots and a very strange hall of mirrors, is also in the void. As is a slaver ship filled with the time-riding Tharils, and captained by the increasingly unstable Rorvik...

Nowhere, literally - the Zero Point between the positive and negative universes. The TARDIS materialises in a white void, but the travellers are not alone. A stone gateway, filled with ageing warrior robots and a very strange hall of mirrors, is also in the void. As is a slaver ship filled with the time-riding Tharils, and captained by the increasingly unstable Rorvik...

Nowhere, literally - the Zero Point between the positive and negative universes. The TARDIS materialises in a white void, but the travellers are not alone. A stone gateway, filled with ageing warrior robots and a very strange hall of mirrors, is also in the void. As is a slaver ship filled with the time-riding Tharils, and captained by the increasingly unstable Rorvik...

Nowhere, literally - the Zero Point between the positive and negative universes. The TARDIS materialises in a white void, but the travellers are not alone. A stone gateway, filled with ageing warrior robots and a very strange hall of mirrors, is also in the void. As is a slaver ship filled with the time-riding Tharils, and captained by the increasingly unstable Rorvik...