Before the Doctor can settle down to married life, he must face one last confrontation with his deadly enemy of certain death - the Master.

The TARDIS materialises at a secret naval base off the coast of Northumberland toward the end of the Second World War. Dr Judson, a scientist there, has created the Ultima Machine, an early computer designed to break German codes. The base's Commander Millington plans to let a Russian commando unit led by Captain Sorin steal the Machine's core, which he has booby-trapped with deadly toxin. Judson uses the Machine to translate some ancient runes from the crypt of the nearby St Judes church and this leads to the release of Fenric, an evil entity from the dawn of time whom the Doctor trapped seventeen centuries earlier in a Chinese flask by defeating it at chess. The flask was later stolen and buried at the church by Vikings. The base and church are attacked by Haemovores. These are humans who have been transformed into hideous vampiric creatures by the Ancient Haemovore - the last survivor of a pollution-ravaged future Earth, who has been brought back in time by Fenric. Fenric takes over Judson's body to challenge the Doctor to a rematch at chess, and Ace unwittingly helps it to win. Fenric, now in Sorin's body, reveals that Ace, Judson, Millington, Sorin and Wainwright, the vicar of St Judes, are all 'Wolves of Fenric' - pawns in its battle against the Doctor. It now plans to release the deadly toxin but the Doctor succeeds in turning the Ancient Haemovore against it and its host body is killed by the gas. The baby daughter of a young woman whom Ace helped to escape from the Haemovores is revealed to be her future mother.

The Doctor and Ace arrive at a secret military base during World War II, where an ancient evil from the Doctor's past prepares to make his final deadly move. As hideous vampires rise from the sea and Russian commandoes begin to close in, they are confronted not only with a mystery from the distant past but also a terrifying vision of mankind's future...

The planet Peladon has applied to join the Galactic Federation, and The Doctor is mistaken for the chairman of the committee sent to assess its application, while Jo is taken for an Earth princess, with the mythical curse of Aggedor apparently striking chancellor Torbis dead, The Doctor must discover who is desperate to stop Peladon joining, but soon he is sentenced to death and his only Allies seem to be Jo and the Ice Warrior Delegates.

The TARDIS lands in a space museum on Earth in the late 21st century, where the Second Doctor, Jamie and Zoe learn that contact has been lost between Earth and the Moon. In this era, instant travel — T-Mat — has revolutionised the Earth. Its people have lost interest in space travel. The Doctor and his companions travel to the Moon in an old-style rocket and reach the Moonbase, control centre for T-Mat, only to find a squad of Ice Warriors have commandeered the base and plan to use the T-Mat network to their advantage.

The Doctor and Leela must catch a killer on a vast mining ship run by robots and humans.

Astronauts rescued from a mission to mars are kidnapped when they arrive back on earth. They seem to have been irradiated, and can now kill people merely by touching them. But the Doctor discovers the astronauts have been replaced with Alien ambassadors who are being forced to behave in a hostile manner. With The Doctor traveling to the alien mother ship, and Liz kidnapped, The Brigadier is left wondering who to trust.

The Doctor and UNIT investigate a deadly infection lurking underneath the Welsh mining town of Llanfairfach. It's an adventure that will change Jo Grant's life forever...

An energy drain traps the Third Doctor and Sarah Jane Smith on the planet Exxilon with its hostile natives, causing the travellers to make an uneasy alliance with a Marine Space Corps expedition and a squadron of Daleks. The key to escape for all of them lies at the heart of a powerful and mysterious lost city, but only after a series of deadly traps.

The Doctor and Ruby Sunday have faced the Bogeyman, fought against Maestro, and survived the battlefield of Kastarion 3. In the epic two-part season finale, The Doctor and Ruby arrive at UNIT headquarters on a top-secret mission and a long-buried secret awaits…