The Zygon Invasion (TV story)

 was the seventh episode of the ninth series of Doctor Who produced by BBC Wales.

Synopsis
A long time ago, the Doctor made a deal in the Tower of London. 20 million Zygons walk among us, in human form, living undetected in peace and harmony. But cracks are showing in this delicate peace. Humans and Zygons are disappearing. In city apartment blocks, lifts are going missing, and far below the streets of Britain, alien pods are growing in secret caverns. To top it all off, UNIT's scientific advisor, Osgood, sends a desperate message to the Doctor - but since Osgood is long dead, how is that even possible?

The Doctor, Clara and UNIT must scatter across the world in a desperate bid to set her free. But in a world of shape-shifting aliens, who can you trust?

Plot
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Cast

 * The Doctor - Peter Capaldi
 * Clara - Jenna Coleman
 * Osgood - Ingrid Oliver
 * Kate Stewart - Jemma Redgrave
 * Jac - Jaye Griffiths
 * Claudette - Cleopatra Dickens
 * Jemina - Sasha Dickens
 * Colonel Walsh - Rebecca Front
 * Little boy - Abhishek Singh
 * Little boy's mum - Samila Kularatne
 * Hitchley - Todd Kramer
 * Lisa - Jill Winternitz
 * Norlander - Gretchen Egolf
 * Hitchley's mum - Karen Mann
 * Walsh's son - James Bailey
 * Zygons - Aidan Cook, Tom Wilton, Jack Parker

Uncredited cast

 * Bonnie - Jenna Coleman
 * Voice of the Zygons - Nicholas Briggs

Crew
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The Doctor

 * A portrait of the First Doctor is hung in UNIT's safehouse.

Clara

 * Clara's voicemail greeting says she's either on the Tube or in outer space. In her case, of course, it's not a joke.

Zygons

 * After the Human-Zygon peace treaty, seen in TV: The Day of the Doctor it is revealed that 20 million Zygons were relocated around the United Kingdom. It quickly became clear that these Zygons had seized control of the UK and had slowly spread across the entire globe.

Story notes

 * The Radio Times programme listing was accompanied by a small colour shot of Osgood and the Doctor, with the accompanying caption "Doctor Who / 8.15 p.m. Osgood is snatched by aliens, prompting a round-the-world rescue mission".
 * Given that the real Clara appears in only one scene, this is technically the second consecutive "companion lite" episode of Series 9.

Ratings

 * BBC One: 3.87m

Filming locations
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Production errors
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Continuity

 * The human/Zygon treaty is referenced (TV: The Day of the Doctor) Since then, a version of Osgood has died. (TV: Death in Heaven)
 * Kate mentions a previous attempt at invasion by the Zygons which occurred in the 1970s or 1980s. (TV: Terror of the Zygons)
 * Kate still confuses the UNIT timelines. (TV: The Day of the Doctor)
 * Osgood reminds the Doctor that he used to wear a lot of question marks on his clothes (TV: The Leisure Hive-Survival) when he comments on her question mark jumper, an allusion to his seventh incarnation. (TV: Time and the Rani)
 * The Doctor says he never stopped wearing question marks as he wears question mark underpants. His eighth incarnation wore question mark boxer shorts. (PROSE: Seeing I, COMIC: The Glorious Dead)
 * A weapon called the ZX-7, confiscated by the Doctor, was invented by Harry Sullivan shortly after he left the Fourth Doctor. (TV: Terror of the Zygons)
 * Clara is once again shown has having authority with UNIT up to and including being able to command UNIT soldiers to use deadly force. (TV: The Magician's Apprentice)
 * Clara is kidnapped by the Zygons and replaced with a Zygon duplicate called Bonnie. This is the fourth occasion that a companion or assistant of the Doctor has been copied by a Zygon (Kate Stewart and Osgood were both copied in The Day of the Doctor, whilst Harry Sullivan was copied in Terror of the Zygons and Lucie Miller in The Zygon Who Fell to Earth).
 * The Doctor resumes his title of President of Earth, and requests use of his presidential plane. (TV: Death in Heaven, COMIC: The Hyperion Empire)

DVD releases
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Blu-ray releases
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