The Zygon InversionSeries Episode Number: 821
World Premiere: Sat 7 Nov 2015 - 8:00pm GMT [BBC One] (United Kingdom)
First Broadcast: Sat 7 Nov 2015 - 9:00pm EST [BBC America]
Running Time: 46 minutes 20 seconds
6.03 Million (UK)Appreciation Index: 84 (UK)
Audience Share: 25.1% (UK)
Chart Position: 24 (BARB Week Top 30 Chart) (UK)
Shapeshifting Zygons are everywhere in the UK, and there is no way of knowing who to trust. With UNIT neutralised, only the Doctor stands in their way. But how do you stop a war? And what can the Doctor do to save his friends?