The time travellers have escaped from the Daleks, but left a vital piece of the TARDIS behind. Getting it back will mean pushing the Thals to mount a dangerous operation.

Ian, Barbara and the Thals struggle through the caves to reach the Dalek city. Will they get there in time? Is there even a way through the treacherous caves? And what are the Daleks planning?

Time is running out as the Doctor and his companions try to defeat the Daleks before they wipe out all life on Skaro.

The Doctor and Ian are taken to the Dalek saucer while Susan and Barbara join the rebels in planning an attack.

The Doctor manages to escape from the Dalek saucer and meet up with Susan and David but Ian is left trapped onboard. Meanwhile, Barbara and her new friends face a dangerous journey across London.

While Susan and David try to find a way out of London, Ian and Larry infiltrate the Dalek mine workings.

The Doctor's party investigate the Daleks' central control in Bedfordshire while Barbara and Jenny's attempt to reach it are derailed when they are betrayed.

The Daleks' plan to transform Earth into a giant spaceship and wipe out its inhabitants is nearing completion and the Doctor and his friends face a race against time to prevent them from destroying the planet's core.

While Ian tries to force Lobos to release the Doctor from the museum, Vicki joins the Xerons in trying to gain the weapons needed to start a revolution against the occupiers.

The Doctor, Jamie and Waterfield follow the Daleks to Skaro, where they discover an unforeseen consequence to their experiment.

The Daleks are poised to spread the Dalek Factor throughout the history of Earth and begin by implanting the Doctor.

When someone tries to assassinate diplomat Sir Reginald Styles, UNIT investigate the possibility his attacker came from the future.

Jo uses the guerrillas' time machine to travel to the 22nd century where the Controller tricks her into telling the Daleks where she's come from.

The Doctor forces the guerrillas to take him to the 22nd century where he is soon captured by the Controller.

The guerrillas infiltrate the Daleks' base to rescue the Doctor and Jo and ask them to return to their own time and alter history before the 20th century is plunged into a Third World War.

The Doctor, Williams and the Draconian Prince head to the Ogrons' planet to find evidence of the Master's actions but the Master tricks Jo into leading them into a trap.

The Doctor is captured by the Daleks, while Jo is rescued by a friendly Spridon named Wester.

The Doctor and Codal escape from their cell and meet up with the Thal commandos who are trying to get into the Dalek base.

The Doctor and his friends escape from the Dalek base, prompting the Daleks to devise a plan to wipe them out.

The Doctor and his friends ambush two Daleks as part of their plan to get back into the city, but the Daleks are on the verge of unleashing their virus.

The Doctor and his friends prepare to refreeze the Dalek army but the Dalek Supreme has arrived on the planet determined to destroy them all.

The barren planet Exxilon, some time in the future. The TARDIS is forced down by a total power failure and the Doctor and Sarah meet a stranded Earth crew who came here to mine for priceless medical supplies. But what is causing the power failures? And why have the Daleks come here too?

The Doctor and the MSC crew join forces with the Daleks to mine the parrinium, only to come under attack from the Exxilons.

The Doctor and Sarah meet up with Bellal, who helps them escape from the Daleks and explains the origin of the City.

The Doctor and Bellal continue to penetrate the City's defences while Sarah and Jill try to stop the Daleks leaving with the parrinium.