The TARDIS materialises on Earth in the year 1911 inside an old priory owned by Egyptologist Marcus Scarman. Scarman has been possessed by Sutekh, last survivor of the god-like Osirans, who is held prisoner inside a pyramid in Egypt by a signal transmitted from one on Mars. Sutekh desires his freedom and instructs Scarman to construct servicer robots - which look like Egyptian mummies - to build a missile with which to destroy the Martian pyramid. The Doctor foils this plan by blowing up the missile.

Humans want the Sensorites' molybdenum.

Spacemen poison the Sensorites' water.

The villainous slave ship commander Rorvik has deadly plan for Romana.

Time begins to run wild; on a planet that shouldn't exist, in the aftermath of apocalypse, the Doctor, Dan, Yaz and Vinder face a battle to survive.

Devon, November 1967; a little girl has gone missing; Professor Eustacius Jericho conducts psychic experiments; and in the village graveyard, there is one gravestone too many.