Terrorists seize the Turkish embassy in London and take Zoe hostage.

A drug sting apparently goes bad resulting in the death of an informant. Devlin feeling something was not right about the situation digs into the past of the involved detective. Unfortunately this brings up a question of Brooks involvement in a drug theft from six years earlier.

UNIT investigates when scientists go missing kidnapped by an alien trapped in the 13th Century. Travelling back in time in the TARDIS, the Doctor is unaware that he has stowaway.

As the repairs to Linx's spaceship are completed and he prepares to take off, the Doctor races to save the captured scientists and to prevent the course of history being changed.

Linx is providing advanced weaponry to Irongron and his men who prepare to attack Sir Edward's castle. The Doctor is forced to improvise a defence, but will it be enough?

The Doctor discovers that the alien is a Sontaran warrior called Linx who is trying to repair his spaceship. Sarah is convinced that the Doctor is responsible for the abductions.

David Suchet and Geoffrey Palmer guest star. The team form a line of defense against groups of mercenaries and guerrillas waging war on the streets of Britain.

When a television crew arrives to make a show about the hospital, the patients fight for stardom.