Ivanhoe, a worthy and noble knight, the champion of justice returns to England after the holy wars, and finds England under the reign of Prince John and his henchmen and finds himself being involved in the power-struggle for the throne of England.

A heavy fog cuts the small isolated Scottish island off from the mainland, and dentist Michael Gaffikin has just discovered a dismembered corpse on the golf links. Michael and his artist girlfriend, Fiona Patterson, assist the local law enforcements in searching for the murderer. However, as the body count rises and the surrounding circumstances turn increasingly bizarre and gruesome, everyone begins to wonder if the killer is a human or an unimaginable creature...

UNIT is providing security cover at an experimental drilling project at Eastchester, designed to penetrate the Earth's crust and release a previously untapped source of energy. Soon, however, the drill head starts to leak an oily green liquid that transforms those who touch it into vicious primeval creatures with a craving for heat. The Doctor is accidentally transported "sideways in time" by the partially repaired TARDIS control console into a parallel universe where the drilling project is at a more advanced stage. Thwarted by his friends' ruthless alter egos, he works to save both universes.

When scientists in the Antarctic uncover a mysterious seed pod, the Doctor is called in to investigate. He soon realises it is extraterrestrial and extremely dangerous. At the same time, however, ruthless millionaire plant-lover Harrison Chase has learned of the find and decides he must have the pod for his collection of rare and beautiful flora. Meanwhile the pod itself harbours intelligent life with sinister plans of its own...

The Doctor, Jamie and Zoe return to Earth and become embroiled in the schemes of Tobias Vaughn. They meet up with an old friend, Colonel (now Brigadier) Lethbridge-Stewart, and some old enemies, the Cybermen.

When the Doctor, Sarah Jane and Harry arrive in Scotland, having received an urgent request for assistance from the Brigadier, they discover that the mysterious force which has destroyed three oil rigs has left giant teeth marks on the wreckage. The mystery deepens, leading them to the shores of Loch Ness where they find that the legendary monster really does exist – and is the murderous tool of the Zygons, aliens intent on overpowering the planet. The Doctor, his companions and UNIT must find a way to defeat the deadly Loch Ness Monster and its controllers, but the Zygons have the terrifying power to change shape. The Doctor's life has never been in more danger, as the line between allies and enemies is tested to the very limit...

When the TARDIS malfunctions, it and its travellers land on Earth at the size of insects. They uncover a murderous plot involving a new insecticide, but how can they stop the crime in their miniaturised condition?

In 12th century Palestine, the Doctor and his friends are drawn into the holy war between the forces of King Richard the Lionheart and the Saracen ruler Saladin.

The Doctor and his companions are pursued through time and space by the Daleks on the desert planet Aridius and beyond.

In England, 1066, the Doctor confronts a mysterious Monk who is attempting to change history.