Gallifrey is in a state of crisis, facing destruction at the hands of an overwhelming enemy. The three incarnations of the Doctor must join together to set time back on the right track—but in doing so, will they unleash a still greater threat?

2000 years ago, a volcanic eruption wiped the city of Pompeii from the face of the Earth. It also buried the Doctor's TARDIS...Arriving in Pompeii the day before the disaster, the Doctor and Mel find themselves dangerously entangled in local politics...

The TARDIS lands in a forbidding castle at a time of religious upheaval. The old god has been overthrown, and heretics are to be slaughtered. Hailed as messengers from heaven, the Doctor and Frobisher soon become embroiled in a deadly struggle for power.

While a NASA team investigate an 'anomaly' on Mars, the Doctor and Peri find themselves inside a strange alien building. What is its purpose? And what is frozen inside the blocks of ice that guard the doorways?

In a desolate Cornish landscape littered with relics of prehistoric man, the Doctor and Evelyn uncover a catalogue of mysteries. Teaming up with the Brigadier, the Doctor realises that an ancient conflict is nearing its conclusion...

The prehistoric Earth is dying. The seas crash and boil as the rain turns to acid. The remnants of the Silurian race place themselves in suspended animation, deep below the surface. One day they will awaken and reclaim their world...

Is wealthy heiress Ileana de Santos all that she seems? What sinister ailment afflicts her invalid son, tended by the mysterious Dr Hayashi? And who exactly is Rosa, engaged on a secret quest to fulfil the destiny of her extinct tribe?