Time Unknown, Planet Unknown. The TARDIS lands in an eerie petrified forest overlooking a magnificent steel city. The Doctor wants to explore the city – but what is waiting there?

The dead planet is not uninhabited after all. The Doctor is about to meet what will become his greatest enemies. And he and his crew are dying of radiation sickness.

Imprisoned on Skaro by the scheming Daleks, the Doctor and his companions work to escape their clutches.

The time travellers work desperately to both escape the Dalek city and prevent a bloody massacre.

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 TARDIS experiences a total power failure and is stranded in the Himalayas in the 13th century. The travellers are forced to join the caravan of the famous explorer, Marco Polo, in order to survive -- but Polo, fascinated by their claims that the TARDIS can fly through the air, seizes it on behalf of Kublai Khan in the hope that presenting the Khan with such a fabulous gift will convince him to let Polo return home to Venice. The travellers are forced to accompany Polo on his long trek across Asia to the Khan's court, but their many attempts to reclaim their property are foiled -- not just by Polo, but by the war lord Tegana, who is apparently on a mission of peace but has entirely different plans for dealing with Kublai Khan...

Tegana sabotages the party's water bags, leaving them in dire need of fresh supplies.

The Doctor and Susan are able to supply Marco with condensation that has formed inside the TARDIS, saving the group from dying of thirst. When the group are reunited with Tegana, the travellers begin to suspect he is up to something.

The Doctor's group manage to rescue Barbara from the Mongols but once more Marco remains unaware of Tegana's involvement.

The Doctor and his friends elect to warn Marco of Acomat's attack even though it means losing their chance to gain access to the TARDIS.

The Doctor, Ian and Barbara are forced to surrender to Tegana and Marco, leaving both of them the opportunity to gain possession of the TARDIS.

Tegana finally makes his move to assassinate the Khan, giving the Doctor and his friends an opportunity to thwart his plans and regain the TARDIS.

The Doctor runs afoul of the Daleks and Special Security Agent Bret Vyon on the planet Kembel.

The Doctor infiltrates the Daleks' conference to try and discover their plans, leaving Steven, Katarina and Bret to find a way off the planet.

The Doctor and his friends escape Kembel in the Spar ship but the Daleks force them down on the planet Desperus, where they are threatened by a group of convicts.

With Katarina being held hostage, the Doctor, Steven and Bret are in danger of having to given in to Kirksen's demands, while, on Earth, Chen has them listed as traitors.

The Doctor, Steven and Sara are accidentally transported to the planet Mira where Chen sends the Daleks after them.

The Doctor, Steven and Sara escape Mira in a Dalek pursuit ship but when they find the ship is returning to Kembel, they are forced to come up with a new plan to avoid the Daleks.

The Doctor, Steven and Sara visit a Liverpool police station on Christmas Day and a Hollywood film set during the 1920s.

The Daleks realise the Doctor has given them a fake Taranium Core while, on the planet Tigus, the Doctor encounters the Meddling Monk.

The Doctor, Steven and Sara travel to Ancient Egypt, pursued by both the Daleks and the Meddling Monk.

Steven, Sara and the Monk are captured by the Daleks in order to force the Doctor to hand over the Taranium Core.

The Doctor, Steven and Sara reach Kembel where they find the Daleks have betrayed their allies and imprisoned them.

With the Daleks poised to invade the solar system, the Doctor decides his only option is to activate the Time Destructor prematurely, threatening the entire planet.

The TARDIS arrives in Tombstone, Arizona in 1891. Where the Doctor is looking for a dentist when he has a toothache, where The Doctor finds the local dentist is the famous Doc Holliday who is in a feud with The Clanton Brothers and their hired gunfighter Johnny Ringo, whilst local sheriff Wyatt Earp is trying to keep the peace. The Doctor, Steven and Dodo find themselves joining forces with The Clanton Brothers and Sheriff Wyatt Earp.

With the Clantons believing the Doctor to be Doc Holliday, Wyatt Earp takes him into protective custody but this leaves Steven and Dodo in danger.

Earp comes to Steven's rescue and arrests Phineas Clanton, prompting the Clantons to decide to enlist the help of Johnny Ringo.

The Clantons have shot Warren Earp, leading to a showdown between the two families with the Doctor powerless to prevent bloodshed.

The Doctor and Quinn attempt to escape in order to stop Bragen using the Daleks to take over the colony.

The Doctor and Jo arrive on the planet Solos, on a assignment by the Time Lords, where they learn that the native Solonians are mutating into ant-like mutant creatures...

Ky transports himself and Jo down to Solos and the Marshal only agrees to help her if the Doctor assists Professor Jaeger in altering Solos' atmosphere.

The Doctor and Varan travel down to Solos to search for Jo and Ky but the Marshal orders his men to pursue them.

The Doctor and his friends are led to safety by Professor Sondergaard, who tries to help the Doctor translate the tablets.

The Marshal's premature use of Jaeger's experiment is threatening to destroy Solos' atmosphere and the Doctor returns to Skybase to try and correct the damage.

The Doctor is forced to help the Marshal cover up his actions with the Investigator but Jo and the others attempt to escape to expose him.