The Zygon Inversion
Set in present-day London, the episode involves Bonnie, the leader of a splinter group of shapeshifting aliens called Zygons, taking the form of the Doctor's companion Clara Oswald (played by Jenna Coleman).
Bonnie intends to use an object called the Osgood Box to unmask 20 million Zygons on Earth, thereby starting a war against humanity.
In the present, Bonnie, the leader of a splinter group of shapeshifting Zygons, has taken Clara's form, keeping her body in a pod.
In interrogating Clara via their telepathic connection, Bonnie learns the Osgood Box is in the UNIT Black Archive under the Tower of London.
UNIT leader Kate Stewart, having survived the encounter with the Zygon in New Mexico,[N 1] reconvenes with the Doctor and Osgood in London.
Eventually, after the Doctor admits the consequences he had to live with since the Time War, both Bonnie and Kate back off with the former realising the boxes are empty and were only a ploy to avoid a disaster.
Later, the Doctor offers Osgood a chance to ride in the TARDIS, but she refuses and instead reveals her new duplicate – Bonnie, who has taken a new form after giving up Clara.
[3][4] UNIT's Black Archive, first seen in the Sarah Jane Adventures story "Enemy of the Bane" (2008) and containing items from several past episodes, currently has a Mire battle helmet first seen in "The Girl Who Died" (2015).
[11] "The Zygon Inversion" received positive reviews, with many highlighting Capaldi and Coleman's performances and the episode's political themes as its best attributes.
"[12] Steven Cooper of Slant Magazine called it the best episode of the season so far and claimed it was "a powerful conclusion to the story set up last week".
[22] Mark Rozeman of Paste Magazine praised the transformation from "standard aliens-invade plot line" to "a treatise about war and its ultimate uselessness."
[24] Mark Rozeman of Paste Magazine awarded the episode a score of 8.8 out of ten, praising Clara and Bonnie's sequences as "brilliantly conceived".
He then closed his review by claiming "The simplicity of [the] setup allows this two-parter to be one of the show's strongest ever statements against war, not because the Doctor is challenging us from on high to live up to his standard, but rather because he wants no one else to know his pain".
