The TARDIS suffers a power drain and is forced down on the planet Exxilon. Sarah is captured by the primitive inhabitants and the Doctor comes face to face with his oldest enemies.

Starring Colin Baker and Patrick Troughton
A three-part story by Robert Holmes
With the aid of the Sontarans, Dastari has secured a base in Spain, but not, alas, to bask in the sun.
*CEEFAX SUBTITLES

Kirsten O'Brien is a television presenter, best known for her CBBC work (alongside Otis the Aardvark) and in art programme SMart.

Ronan Vibert played Nicholas Skinner in The Sarah Jane Adventures television story The Last Sontaran.

Credits include 1066, Saving Mr. Banks, Hatfields & McCoys, The Borgias, The Jury II, Agatha Christie: Poirot, The Bill, Hotel Babylon, Rome, Hex, Waking the Dead, Keen Eddie, The Scarlet Pimpernel, The Canterbury Tales, Gimme Gimme Gimme, Big Women, The Buccaneers, 99-1, Jeeves and Wooster, Traffik

Emilia Jones portrayed Merry Gejelh in the 2013 story The Rings of Akhaten.

She was born In February 2002 and since the age of 8 has attended Saturday classes at The Sylvia Young Theatre School.

She played the part of Young Sarah in the television programme House of Anubis (Nickelodeon USA and UK) andAlice in Utopia, a six part drama series written by Dennis Kelly (Channel 4) 

Film work includes the role of Jasmine in One Day, adapted from David Nicholls' best-selling novel of the same name (Focus Features) and English Girl in Pirates of the Caribbean: On Stranger Tides (Disney).

Jones played Young Fiona in the original West End cast of Shrek The Musical at the Theatre Royal, Drury Lane and Flora in The Turn of the Screw at The Almeida.

Gerry Davis was a British television writer, best known for his contributions to the science-fiction genre. 

From 1966 until the following year, he was the script editor on Doctor Who, for which he co-created the Cybermen. His fellow co-creator of these creatures was the programme's unofficial scientific adviser Dr. Kit Pedler, and following their work on Doctor Who, the pair teamed up again in 1970 when they created a science-fiction programme of their own, Doomwatch. Doomwatch ran for three seasons on BBC One from 1970 to 1972, and also spawned a novel written by Davis and Pedler, and later a cinema film and a 1999 revival on Channel 5.

Davis briefly returned to writing Doctor Who, penning the original script for Revenge of the Cybermen, in 1975, though the transmitted version was heavily rewritten by the then script-editor Robert Holmes. He also adapted several of his scripts into novelisations for Target Books. With Kit Pedler, he wrote the science-fiction novels Mutant 59: The Plastic Eaters (1971), Brainrack (1974) and The Dynostar Menace (1975).

In the 1980s Davis worked in America both in television and on feature films such as The Final Countdown (1980). In late 1989 he and Terry Nation made a joint but unsuccessful bid to take over production of Doctor Who and reformat the series mainly for the American market. He also wrote for the soap operas Coronation Street and United!.

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

Bernard Kay was an english actor born in  Bolton, England. He has an extensive theatre, television and film repertoire.

Kay began his working life as a reporter on Bolton Evening News, and a stringer for The Manchester Guardian. He was conscripted in 1946 and started acting in the army. Kay gained a scholarship to study at the Old Vic Theatre School and became a professional in 1950, as a member of the company which reopened the Old Vic after WW2.

He appeared in hundreds of TV productions including Emmerdale Farm, The Champions, The Cellar and The Almond Tree, Clayhanger, A Very British Coup, Casualty, Casualty 1909, Doctors,  Coronation Street and Foyle's War. He also appeared in the very first episode of Z Cars.

He portrayed Captain Stanley Lord of the SS Californian in the BBC dramatisation Trial by Inquiry: Titanic in 1967; and he played the bandit leader Cordova in Zorro television episode Alejandro Rides Again in 1991 which was filmed in Madrid, Spain. Kay also gave a sympathetic performance as Korporal Hartwig in an early episode of Colditz.

His first film appearance was as an injured recruit in Carry on Sergeant, a role which saw him alongside first Doctor William Hartnell. They would work together again in Doctor Who, with Kay appearing in two stories, most notably as Saladin in the classic Doctor Who story The Crusade in 1965 (which also featured Julian Glover and Jean Marsh, and in the second Dalek adventure The Dalek Invasion of Earth (1964); he later worked alongside Patrick Troughton in The Faceless Ones (1967) and Jon Pertwee in Colony In Space (1971). In 2006, he also guest-starred in the Doctor Who audio adventure Night Thoughts.

His most famous film appearance was his turn as a Bolshevik leader in Doctor Zhivago (1965). 

He also acted extensively on the stage. In 1952, for the Nottingham Rep, he learned, rehearsed, and played Macbeth in less than 24 hours. In 1984, he played Shylock in The Merchant of Venice during a British Council tour of Asia, ending in Baghdad, in the middle of the Iraq/Iran war. Other theatre includes An Inspector Calls (Garrick Theatre), Macbeth (Nottingham Playhouse), Titus Andronicus (European Tour), A Man for all Seasons (International Tour), The Merchant of Venice (International Tour), Galileo (Young Vic), Death of a Salesman (Lyric Theatre, Belfast) and Halpern and Johnson (New End Theatre). He has twice appeared at the Finborough Theatre, London - in 2006 in After Haggerty and in 2010 in Dream of the Dog.

Bill Strutton was a prolific British screenwriter who worked on some of the best-remembered 1960s television shows including Ivanhoe, The Saint, The Avengers as well as Doctor Who.

Born in Australia, Bill Strutton won a state scholarship to university at 14 but dropped out after two years to go and work in an office. At the outbreak of WWII he joined the Australian army. He was captured by the Germans in Crete and sent to Stalag VII, learning to swear in several languages. It was there he also began to take an interest in writing.

After the war he took up journalism as a career and in the mid-fifties he began writing military books, including A Jury of Angels in 1957. In 1958 he scripted Ivanhoe, which starred a young Roger Moore. He wrote for more than 15 television series in 11 years, the last of which was Strange Report, starring Anthony Quayle, and several episodes of Paul Temple before retiring in 1978 following a heart attack.

Laurence Payne was an English actor and novelist.

Laurence Payne was born in London. He attended Belmont school and Tottenham Grammar school, leaving at 16 to take a clerical job. After training at the Bristol Old Vic Theatre School in 1939, he was exempted from war service as a conscientious objector on condition that he went on tour with the Old Vic during the war.

Payne made his professional debut at the Old Vic Theatre in 1939 and remained with the company for several years. He then performed at the Chanticleer and Arts theatres in London, also directing and broadcasting for the first times during this period. At Stratford-on-Avon he played, among other parts, Romeo in Peter Brook's 1947 production.

After more work at London theatres, he played leading roles at the prestigious Bristol Old Vic, and after that rejoined the London Old Vic company. At the Embassy Theatre in London he played Hamlet.

His film credits include: The Trollenberg Terror (aka. The Crawling Eye), Vampire Circus, The Tell-Tale Heart and Ben-Hur. His television credits include: Z-Cars, Moonstrike, The Sandbaggers, Airline, Telephone Soup, and Tales of the Unexpected.

He appears in three Doctor Who serials: The Gunfighters, The Leisure Hive and The Two Doctors, playing a different role in each. 

Perhaps his most famous role was as TV's Sexton Blake (1968-71) on ITV in Britain. It was while filming an episode of Sexton Blake, that he lost the sight in his left eye during rehearsal of a sword fighting scene with actor Basil Henson, following a hard sword blow against the side of his head. Peter Moffatt took him straight away to Moorfields Eye Hospital and Payne was told that if he could lay still for a week without moving his head, his retina would join up again so preserving his sight. Instead of doing this, Payne went back to work, got hit in a fist fight, and so lost his sight in that eye.[citation needed]

After retiring from acting, Payne continued to concentrate on writing crime/detective novels (his first novel having been published in 1961). By 1993, he had published 11 novels.

Roy Heymann  appeared in two Doctor Who stories: as an Alien Priest in Colony in Space and Gotal in Death to the Daleks.

Also appeared in Dixon of Dock Green.

Esmond Knight was an accomplished actor with a career spanning over half a century. For much of his career he was virtually blind, having been badly injured in 1941 whilst on active service on board HMS Prince of Wales when she fought the Bismarck at the Battle of the Denmark Strait.

He remained totally blind for two years, though later regained some sight in his right eye. During this period, Esmond dictated an early autobiography to his secretary, Annabella Cloudsley, Seeking The Bubble. He went on to play the captain of the his old ship in the 1960 film Sink the Bismarck!

He starred as Professor Ernest Reinhart in the 1961 British science fiction television series, A for Andromeda, alongside Patricia Kneale and Peter Halliday.

Knight died in 1987, having suffered a heart attack.