Earth, the future. The genius Sylvest twins, child prodigies, are kidnapped by the mysterious Professor Edgeworth and taken to the planet Jaconda. But who is Edgeworth? Why does he serve the giant slug Mestor? And what is Mestor's plan?

The Doctor takes Peri to Titan 3, a desolate hunk of rock in space where he hopes to find some solitude for a while. Instead he finds the lone but unconscious survivor of a recent spaceship crash in sight of a mound-shaped complex where no formalised structure should exist.

The Doctor arrives on Jaconda, once lush and green, to find it completely devastated by giant gastropods. Old legends about the planet's half-human/half-slugs weren't just myths after all. With or without help from the Doctor and his unpredictable mood swings, Lt. Lang is up for rescuing the twins, who are finally informed of the grand purpose they've been brought to Jaconda to accomplish.

The Doctor and Edgeworth deduce that the real plan of Mestor, the gastropod ruler of Jaconda, will not only destroy Jaconda but lead to the devastation of other planets. Together they hope to thwart him despite his formidable ability at slipping into people's minds and controlling them.

The Governor forces the Doctor to tell him the true value of zeiton-7 but Sil attempts to derail his plans by subjecting Peri and Areta to an enforced mutation.

The Borad accepts no opposition and enables Maylin Tekker to expose the rebels and trap Peri with the Morlox. The Doctor tries to avert a war between Karfel and the Bandrils.

The planet Karfel, in the distant future. The tyrannical Borad rules with an iron fist, and any who oppose him are cast into the Timelash - a space-time tunnel leading to the past of an alien world called Earth...

The former prison planet Varos, the future. The downtrodden population of miners are kept happy by real-life violence and murder broadcast live from the Punishment Dome. But then the TARDIS materialises inside the Dome...

The TARDIS materialises on a deserted beach where the Doctor and his friends are captured by primitive warriors and taken to the fabled city of Atlantis.

With Zaroff's plan nearing completion, the Doctor and Ben realise the only way to save the world is to destroy Atlantis.

The Master uses The Rani's mind-controlling parasites to keep a meeting of Earth's leading scientists from being cancelled, and helps her plant transformation land mines for The Doctor, as he continues to propose an alliance with her in ruling over Earth.

The Sontarans prepare the Second Doctor to trigger their Kartz-Reimer capsule.

While Ara tries to save Polly from being turned into a Fish Person and Ben and Jamie try to escape from the mines, the Doctor discovers the full extent of Zaroff's plans.

Zoe and Cully are captured by the Dominators and put to work alongside the survey team while the Doctor and Jamie decide to return to the island to help.

The Doctor and Zoe are interrogated by Rago, who is planning to present his terms to the Dulcian council, while Jamie and Cully try to find a way to strike back against the Quarks.

Jamie and Cully manage to rescue the Doctor's party and together they try to find a way to stop the Dominators before they destroy the entire planet.

The Doctor enters the labyrinth to try and protect Jo from the minotaur but the Master has seized control of Atlantis and prepares to summon Kronos again.

England, the 1820s. As the Industrial Revolution gathers pace, the village of Killingworth is disturbed by crazed Luddite miners intent on smashing all machinery and engineers. But is there another cause of the situation?

The Doctor and Peri meet Jamie and learn the Second Doctor is with the Sontarans on Earth.

Davros plans to create an army of Daleks loyal only to him but on Skaro, the Daleks have other plans and head to Necros. Caught in the middle of this, the Doctor must save Peri...

The Doctor and Ramo are sentenced to be sacrificed to the goddess Amdo and must escape to put a stop to Zaroff's plan.

The planet Peladon, some time in the future. Mining disputes threaten the peace of the planet, and as the Doctor and Jo arrive, it seems that the ghost of Aggedor walks once more...

The Third Moon of Delta Magna, The Future. The Doctor and Romana arrive in search of the fifth segment and are immediately swept up in a conflict between the crew of a new refinery and the embittered natives…

The alien space station J7, the mid-1980s Earth time. The Time Lords have sent the second Doctor and Jamie here to try to stop dangerous experiments into time travel. But the station comes under attack from the Sontarans and far away in space and time the sixth Doctor goes into psychic shock...

The planet Necros, the future. The Doctor arrives for the cryogenic interment of an old friend at Tranquil Repose, a vast repository of bodies in suspended animation. But what does the 'Great Healer' really have in mind for them...?