In a brief preview video, Doctor Who stars Pete Capaldi and Jenna Coleman discuss the upcoming episode, "The Zygon Invasion," in which the truce bartered with the Zygons in "The Day of The Doctor" breaks down. Capaldi refers to the nature of the titular invasion as "something different." Surprisingly, Saturday's episode marks only the third television appearance of the shape-shifting, but soft-spoken aliens — in their native form — in the show's history. A group of Zygons briefly appeared in the 2012 story, "The Power of Three," disguised as staff of the Savoy Hotel.
The new episode Doctor Who airs tomorrow, October 31st.