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.

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.

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

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

With Clancey and Issigri trapped aboard the LIZ, the Doctor, Jamie and Zoe try to convince Madeleine to help them before Caven destroys Ta.

The Doctor is forced to co-operate with the Animus but Ian uses the opportunity to make an escape attempt.

Barbara and the surviving Menoptera take refuge in the Temple of Light while the Doctor and Vicki attempt to escape by taking control of a Zarbi.

The Doctor and Vicki are taken before the Animus but the isoptope is left behind in the laboratory.The only hope of victory lies with Barbara and her Menoptera allies.

Madeleine is revealed to be working with Caven, who comes up with a way to kill the Doctor and his friends whilst framing them for the piracy.

The Doctor, Ian and Vicki are captured by the Zarbi while Barbara meets up with the butterfly-like Menoptera who are trying to reclaim the planet.

Ian and Vrestin are captured by the subterranean Optera while Barbara and her Menoptera allies attempt to escape from the slave camp.

While the Doctor continues to play the Trilogic Game with the Toymaker, Steven and Dodo are involved in a deadly game of musical chairs.

Steven and Dodo are forced to cross the dancing floor, where the Toymaker's dolls plan to force them to dance for eternity.

The Doctor, Jamie and Zoe flee from the Space Corps with Clancey, who decides to seek refuge on Ta.

The Doctor, Jamie and Zoe are held prisoner by the space pirates while Caven comes up with a plan to throw suspicion onto Clancey.

Space beacons are being destroyed by pirates, who are salvaging the argonite metal. When the Doctor, Jamie and Zoe arrive on one of the beacons, they are mistaken for pirates.

The TARDIS is drawn by a mysterious force and lands on the alien planet Vortis. There the Doctor, Ian, Barbara and Vicki find themselves caught up in a war between an evil force known as "The Animus", its ant-like Zarbi allies, and the butterfly-like Menoptra race and their allies the subterranean Optera.

While the Doctor, Ian, and Vicki are drawn into the intrigues of King Richard's court, Barbara has to cope with an impatient Saladin and the vengeful El Akir.

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.

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 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.

While Odysseus forces the Doctor to find a way to win the war, Steven decides to get himself taken prisoner in order to enter Troy and find Vicki and the TARDIS.

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

The Monoids abandon the Ark, leaving Steven and the Guardians to die, but a mutiny in their ranks may give the Doctor a chance to bring about peace.