The world of Thra is changing. The Skeksis, alien vulture-like creatures who have ruled over the native Gelflings for hundreds of years, have plundered the power of the Crystal to sustain themselves, and this is beginning to influence Thraian lifeforms in sinister ways. Most of the Gelflings are extremely gullible and view the obviously evil Skeksis as benevolent lords, but one or two are beginning to smell a rat. Junior guards Rian (Taron Egerton and Neil Sterenberg) and Mira (Alicia Vikander and Helena Smee) are searching the Skeksis castle for an escaped Spitter when they have an unfortunate encounter with the Skeksis chief scientist; meanwhile Gelfling princess Brea (Anya Taylor-Joy and Alice Dinnean) becomes suspicious of the tributes offered to the Skeksis lords during the annual tithing ceremony, and underground-dwelling Deet (Nathalie Emmanuel and Beccy Henderson) discovers that her favourite baby nurloc has become a little irritable. Something isn't quite right. Set before...