The Zygon Invasion

258a – "The Zygon Invasion"
Doctor Who episode
The episode sees the returns of the Zygons and Osgood (Ingrid Oliver).
Cast
Doctor Peter Capaldi (Twelfth Doctor)
Companion Jenna Coleman (Clara Oswald)
Others Ingrid Oliver – Osgood Jemma Redgrave – Kate Stewart Rebecca Front – Colonel Walsh Jaye Griffiths – Jac Cleopatra Dickens – Claudette Sasha Dickens – Jemima Abhishek Singh – Little Boy Samila Kularatne – Little Boy's mum Todd Kramer – Hitchley Jill Winternitz – Lisa Gretchen Egolf – Norlander Karen Mann – Hitchley's Mum Aidan Cook – Zygon Tom Wilton – Zygon Nicholas Briggs – Voice of the Zygons (uncredited)
Production
Directed by	Daniel Nettheim
Written by	Peter Harness
Script editor	David P Davis
Produced by	Peter Bennett
Executive producer(s)	Steven Moffat Brian Minchin
Incidental music composer	Murray Gold
Series	Series 9
Length	1st of 2-part story, 45 minutes
Originally broadcast	31 October 2015 (2015-10-31)
Chronology
← Preceded by Followed by → "The Woman Who Lived" "The Zygon Inversion"
List of Doctor Who serials

Professional ratings
Review scores
Source	Rating
Rotten Tomatoes (Tomatometer)	94%
Rotten Tomatoes (Average Score)	7.7
The A.V. Club	B+
Paste Magazine	7.9
SFX Magazine
TV Fanatic
IndieWire	A++
IGN	7.8
New York Magazine
Daily Telegraph
Radio Times

"The Zygon Invasion" is the seventh episode of the ninth series of the British science fiction television series Doctor Who. It was first broadcast on BBC One on 31 October 2015. It is written by Peter Harness and directed by Daniel Nettheim, and was originally titled "Invasion of the Zygons".

In this episode, "Humans and Zygons are disappearing and far below the streets of Britain, alien pods are growing in secret caverns." The episode also sees the return of Osgood, who last appeared in "Death In Heaven" and was vaporized by Missy. The episode also sees the return of the Zygons who were last seen in "The Day of the Doctor".

In the aftermath of the previous Zygon attack on Earth and the Doctor's actions to ensure the creation of a peace treaty ("The Day of the Doctor"), there existed two versions of UNIT scientist Osgood: one human and the other a shapeshifting Zygon duplicate who do not divulge which is which since they considered themselves as both hybridized sisters and the personification of the treaty. Though the treaty allowed 20 million Zygons to remain on Earth, peacefully living out as disguised humans, the Doctor warned the Osgoods of the Nightmare Scenario should the treaty break, and left the Osgoods with a mysterious container they call the Osgood Box. Since that time, one of the Osgoods was killed by Missy; following her death the other left UNIT and disappeared from the grid.

In the present, the remaining Osgood is captured by Zygons in the town of Truth or Consequences, New Mexico just after sending a warning to the Doctor that the Nightmare Scenario has occurred. The Doctor arrives on Earth and speaks with two known Zygon commanders, disguised as schoolgirls, but they are kidnapped by Zygons before he can learn more. He attempts to call Clara as he travels to UNIT headquarters at the Tower of London. Kate Stewart and her assistant Jac show him a video of Zygons killing the two commanders, followed by Osgood being forced to read a message from a small village in Turmezistan, declaring the Zygons' intent to go to war. The Doctor surmises this must be a splinter group as the bulk of the Zygons want to live in peace. Kate reveals that she knows of Z67, a nerve gas that UNIT had developed that would only affect Zygons but that the Doctor had taken away which could end this current situation, but Doctor refuses to let them have it.