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.

Starring Colin Baker
A two-part story by Paula Moore
The Doctor meets up with an old adversary - Commander Lytton. But what should an old foe be doing in the London sewers?

As a terrifying plan to destroy humanity approaches its conclusion, can the Doctor and her friends escape multiple traps to defeat a deadly alliance?

Intelligence agents around the world are under attack from alien forces. MI6 turns to the only people who can help: The Doctor and friends. As they travel the globe for answers, attacks come from all sides.

Ross Mullan, originally from Montreal, Canada, has been living in the UK now for 15+ years. 

He began his performing career working mostly in mask and physical theatre companies and then began writing his own material and playing clubs and bars doing comedy. He then started working in theatre doing National and International tours of shows such as East of Eden, David Copperfield, Christmas Carol and Sherlock Holmes. Ross also played Orsino, in Bath Theatre Royals production of Twelfth Night, the title role of the Selfish Giant for Leicester Haymarket Theatre and brought the critically acclaimed play THICK from the Edinburgh festival to New York City with sold out performances. Ross is also an established Puppeteer and voice over artist having trained with Jim Hensons company many years ago. 

He helped create the character of Zippo the Dinosaur in the Hallmark miniseries Dinotopia, starring Wentworth Miller, with the Computer Generated Image Department filming his every move and nuance. He is the voice and spirit behind the ever lovable Nev the Bear on BBC's Bear Behaving Badly which is now airing its 3rd series. Ross is most recognisable as the evil Numbertaker from Cbeebies hit show Numberjacks which is in its 2nd series. He is in Clash of the Titans (2010) for Warner Brothers playing Pemphredo one of the three blind Stygian witches.

Norman Forber Kay was a British composer and writer.

Kay, who was born in Bolton, was educated at Bolton School, the Royal Manchester College of Music and the Royal College of Music. Kay composed the score for many episodes of Doctor Who, including the very first serial, An Unearthly Child. He went on to contribute music for The Keys of Marinus and The Sensorites, two other stories of the programme's first season (starring William Hartnell).

Besides this work, he also provided the music for many of the Out of the Unknown stories and productions such as Late Night Horror in 1968, as well as many other television and film productions. Kay also worked as a music critic forThe Daily Telegraph.^[3] He was the first British musician to write a study on Dmitri Shostakovich, a work that was well-received.^[1][3]

Kay died in 2001 of Motor Neurone Disease aged 72.

_{Biography from the Wikipedia article, licensed under CC-BY-SA}

Wolfe Morris was a British film and television actor. 

He played Padmasambhava in the Doctor Who serial The Abominable Snowmen.

He played character roles on stage, television and in feature films from the 1950s until the 1990s. He made his film debut in Ill Met by Moonlight. His grandparents were from Kiev and escaped the Russian pogroms, arriving in London in about 1890. The family moved to Portsmouth at the turn of the century. Morris was one of nine children born to Morry and Becky Morris. His younger brother, Aubrey Morris, is also an accomplished actor. His daughter Shona Morris became a stage actress.

In his career, spanning five decades, Morris appeared in almost 90 different films and TV shows, as well as appearing in numerous stage plays as a member of the Royal Shakespeare Company. His best-known role on television was as Thomas Cromwell in The Six Wives of Henry VIII. In preparation for it, he visited a number of English castles to study the characters' portraits. In 1968, he played Gollum in the BBC Radio dramatisation of The Hobbit. In 1975 Morris appeared alongside his younger brother Aubrey in The Adventure of Sherlock Holmes' Smarter Brother.

Continuity on the feature films Dr Who and the Daleks and Daleks' Invasion Earth 2150 A.D