The Zygon Invasion

Plot

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.

Clara is about to answer the Doctor's call when she sees Sandeep, a little boy from a nearby flat, worried about his parents. At his flat, his parents insist all is well and take the struggling boy back in, amid other noises in the flat. Clara leaves and meets the Doctor, as he sends Kate to Truth or Consequences to learn about that town, while he will travel to Turmezistan via the aeroplane afforded him by being President of the World to rescue Osgood. He instructs Clara and Jac to keep the homeland safe.

In Turmeszistan, the Doctor speaks to UNIT Commander Walsh, who explains how the Zygons have been able to take on the appearance of her soldiers' loved ones to prevent any attack on the village. With a bombing run planned, the Doctor joins Walsh and other troops as they converge on the chapel in town. The Zygons, appearing as relatives and friends, lure all the other soldiers into the chapel and kill them, against Walsh's orders. The Doctor and Walsh enter through a back door, finding all the Zygons have escaped. Walsh gives the Doctor a few minutes before she will start the bombing run. The Doctor finds Osgood safe under the chapel, but they are cornered by a Zygon when they try to leave. However, Walsh's early bombing creates debris that knocks the Zygon out. The Doctor and Osgood return to the plane and fly back to England, during which the Doctor attempts to pry information from the Zygon. The Zygon tells him that their invasion has already taken place and his plane will never land.

In New Mexico, Kate finds Truth or Consequences seemingly empty. While at the sheriff's office, she meets Sheriff Norlander who claims to be the last human alive after Zygons that lived among them turned and attacked them when their secret was discovered. While Kate is looking for more clues, Norlander is shown to be a Zygon, and prepares to kill Kate.

At UNIT, Clara has Jac help to get some things from her flat. While there, they see Sandeep's parents dragging a large bag into a lift. When the lift returns, they discover Zygon control units within it, which take them to a series of tunnels under London which many other lifts across the city connect to. They return with a troop of UNIT soldiers to explore the tunnels, and find thousands of Zygon pods which Clara says must be where the Zygons are cloning themselves, and they must be destroyed. When one pod is revealed to contain Clara, Jac realises too late that Clara is a Zygon herself, having been switched when she first went to Sandeep's flat. The Zygon, calling herself Bonnie, states that the invasion has already occurred, with many of the humans in London already captured and replaced by Zygons. Jac and the troops are killed by Zygons when they attempt to escape.

Bonnie travels to UNIT to obtain a shoulder-fired missile, en route learning that the threat in New Mexico has been neutralized. She goes to the coast and contacts the Doctor, informing him of the deaths of his friends. She fires the missile at the plane, and smiles when an explosion is heard.

Continuity

Events from the Fourth Doctor serial Terror of the Zygons are brought up in the episode. Kate mentions this previous Zygon attack taking place in either the 1970s or 1980s, referring to the UNIT dating controversy regarding in which decade the Third and Fourth Doctors' UNIT stories actually took place. Kate references Harry Sullivan, a companion to the Fourth Doctor in this serial, as the "naval surgeon" that helped create the Z67 anti-Zygon nerve gas. Kate states the gas was developed in secret at Porton Down, alluding to Harry's location as reported by the Brigadier in the serial Mawdryn Undead.

Following from her appearances in "The Day of the Doctor" and "Death in Heaven", both Osgoods are shown wearing costume elements of the Doctor's earlier incarnations. In addition to the Fourth Doctor's scarf, one Osgood is shown with a bow tie similar to the Eleventh Doctor's, while the other wears a question mark-decorated tank top similar to that worn by the Seventh Doctor. Both have shirts with question marks on the collar points, a common element of the Fourth, Fifth and Sixth Doctors' outfits. Osgood asks the Doctor why he does not use the question mark motif anymore, to which he replies that he still does - on his underpants.

A portrait of the First Doctor is displayed by the stairs in the UNIT safe house.

The Doctor remarks that he once "snogged a Zygon". The Tenth Doctor kissed a Zygon impersonating Queen Elizabeth in "The Day of the Doctor".

The Doctor resumes the position of "President of the World" and the use of the plane afforded by that position, both mentioned in "Death in Heaven". However, when he introduces himself as President of the World, he is told, "yes, we know who you are." This is continuation of a running joke from earlier in the series; the Prime Minister Harriet Jones is regularly told this after introducing herself, multiple times in both "The Christmas Invasion", and in "The Stolen Earth".

The Doctor suggests that Osgood is a hybrid between a Zygon and human, continuing the theme of hybrids mentioned in "The Magician's Apprentice" / "The Witch's Familiar" and "The Girl Who Died" / "The Woman Who Lived".

Outside references

The Doctor plays the opening to the hymn "Amazing Grace" on his electric guitar.

Clara claims to memorize obscure facts to help her win at Trivial Pursuit, a popular trivia quiz board game. She also explains, from her knowledge of Trivial Pursuit, how the town of Truth or Consequences got its name from the television show Truth or Consequences.

As well as identifying himself as "Dr. Disco", the Doctor also calls himself "Dr. Funkenstein" after a song of the same name by the band Parliament.

Broadcast and reception

The episode was watched by 3.87 million viewers overnight in the UK and received a 19.4%. It received an Appreciation Index score of 82. Overall the episode had 5.76 million viewers.

Critical reception

"The Zygon Invasion" received critical acclaim. Based on 16 critic reviews, the episode holds a score of 94% on Rotten Tomatoes, with an average score of 7.7/10. The site's consensus reads "With "The Zygon Invasion," Doctor Who delivers a thrilling episode that pays special attention to character development and the consequences of time travel". Aspects of the episode particularly praised by critics included the characterisation of Osgood, the cliffhanger ending and the political themes running through the episode.

Tim Martin of The Daily Telegraph awarded the episode four stars out of five, particularly praising Osgood's characterisation as "Earnest, resourceful and an unabashed superfan". Ross Ruediger of New York Magazine highly acclaimed the episode, awarding it five stars out of five. He opened his review by saying that the episode "arguably became the most important Doctor Who episode since “Vincent and the Doctor” tackled depression back in 2010". He also praised Harness' script, saying he did "a great job" with the character of Osgood, and praised the Zygons as "frankly pretty terrifying". He also praised Clara's plot twist, by stating "The episode’s greatest triumph in this area is what was done with Clara, which is shocking on the first viewing and masterful on a second". Scott Collura of IGN also praised the episode, awarding it a score of 7.8, deemed as a "Good" score. He particularly praised the character of Osgood in the episode and the "refugee subtext", while stating that it "poses some thought-provoking questions".

Kaite Welsh of IndieWire highly acclaimed the episode, awarding it a grade of A++, the highest grade possible. Calling the episode a "classic", she further said that it "more than lives up to the hype, with some stellar political commentary, brilliant performances and some very creepy child actors". She further praised the episode's political themes by saying "The parallels between immigration debates aren't exactly subtle here, but they're so well-drawn it's impossible to mind". Alisdair Wilkins of The A.V. Club also enjoyed the episode, awarding it a B+ grade. He said that the episode "is methodical in how it paces the setup for next week's story... But no matter, because there are still plenty of some standout scenes here, in particular Hitchley's standoff with his mother in front of the church". He closed his review by saying "the only real questions to answer are does this episode generate anticipation for next week, and does this episode position “The Zygon Inversion” to go to places and explore things it couldn’t reach if it weren’t the back half of a two-parter? I’d say yes on both counts".