The Doctor and her companions discover the luxury resort where they are staying is hiding a number of deadly secrets; they must discover why there are ferocious monsters attacking Tranquillity Spa.

From ancient Syria, to present day Sheffield and out into the wilds of space, something is stalking the Doctor and her friends; as Graham, Yaz and Ryan return home to see friends and family, they find themselves haunted by very different experiences.

In 12th century England, infamous thief baron Irongron attracts the interest of Sontaran warrior Linx, who has unwillingly landed on Earth. To repair his ship Linx must travel through time, entering the realm of UNIT and Doctor Who.

Doctor Who gets a glimpse of a Sontaran warrior and quickly travels back in time to Medieval England. While making the trip the Doctor realizes noise in the compartment is reporter Sarah Jane Smith who due to circumstance, becomes his companion.

The captured UNIT scientists remain in captivity when the Doctor and Sarah arrive in Medieval England. To make matters worse, Sontaran Warrior Lynx requires scientific expertise to repair his ship and thus forms an alliance with chief Irongron.

The Doctor hopes to rescue the scientists but must first face off against Sontaran Warrior Lynx and chief Irongron, both of whom are intent on stopping him. A primitive weapon however, may be the Doctor's only effective strike against the sinister allies.

In the not too distant future, The Doctor and Sarah return to London which seems to be both deserted and ruled by martial law. Unable to understand why this has happened, they try to find some answers.

Returning to a futuristic London under martial law, The Doctor and Sarah realize dinosaurs roam free throughout the city. The two question how this is possible and who exactly benefits from this chaos.

The doctor realizes a group of extreme environmentalists is behind the resurrection of dinosaurs. They plan to send society back in time to a pre-historic period, and therefore, establish an era without pollution.

Before they are able to warn authorities of the environmentalist plan to send humanity back to the Prehistoric Era, the Doctor and Sarah are sent to prison for looting. Now it is up to their friends at UNIT to come to their aid.

The Cybermen are on the march; as the last remaining humans are ruthlessly hunted down, Graham, Ryan and Yaz face a terrifying fight for survival.

The sinister environmentalists who are responsible for resurrecting the dinosaurs that are terrorizing the streets of London kidnap the Doctor's protégé, Sarah. Now the Doctor aided by his UNIT colleagues find themselves in a larger predicament.

The Doctor and UNIT find out the environmentalists headquarters and are intent on stopping the Pre-historic project in its tracks. Nevertheless, the two evil geniuses behind the scheme have already activated a device which could destroy civilization.

The Borad plans to genetically alter Peri.

The Borad intends to destroy the people of Karfel.

The crew venture out of the Tardis into 15th Century Mexico and the tomb of the Aztec High Priest Yetaxa. When Barbara stumbles upon the Aztecs they mistake her for a reincarnation of the High Priest himself.

Barbara's interference in the Aztec practice of human sacrifice casts doubt over her supposed divinity and puts the whole crew in jeopardy.

It is the day of the solar eclipse when Susan is to be punished for her refusal to marry. The Doctor and his companions try to escape before they are sacrificed to the Sun God.