Professional ratings
Review scores
Source	Rating
Rotten Tomatoes (Tomatometer)	100%
Rotten Tomatoes (Average Score)	7.78
The A.V. Club	B+
Entertainment Weekly	B+
SFX Magazine
TV Fanatic
IGN	8.3
New York Magazine
Radio Times

"The Eaters of Light" is the tenth episode of the tenth series of the British science fiction television series Doctor Who. It is written by Rona Munro and was broadcast on 17 June 2017 on BBC One. Munro previously wrote Survival, the final serial of the original run of Doctor Who, making her the only writer to date to have worked on the classic and revived eras of the show. The episode received mixed reviews from television critics.

The Doctor (Peter Capaldi) takes Bill (Pearl Mackie) and Nardole (Matt Lucas) to second century Scotland to settle their different theories about what happened to the ninth legion of the Roman army that vanished. When they arrive, however, they find an alien menace from another dimension that may be the reason behind the vanishing, but is a far greater threat than any army.

The Doctor and Bill, disagreeing about the fate of the Ninth Legion of the Imperial Roman army, travel in the TARDIS along with Nardole to the 2nd century in Scotland to prove the other wrong. Bill goes her own way to find the Legion, while the Doctor and Nardole look for their dead bodies.

Bill encounters some of the Legion's soldiers hiding underground, the TARDIS' translation circuits helping her communicate with them. The soldiers are hiding from a "Light Eating Locust" that seems drawn to any light source, killing those in its path. Meanwhile, the Doctor and Nardole discover the boneless corpses of the remaining Legion. They later come across a Pict tribe guarding a cairn and waiting for Kar, their leader and the "Guardian of the Gate". The Doctor impatiently enters the cairn, passing into an interdimensional portal full of creatures feeding off a light source. He comes out seconds later, but finds that more than two days have actually passed. Kar explains that once a generation, a warrior of their tribe goes through the cairn to defeat an "Eater of Light", but with the invading Roman army, she allowed one to escape to fight them. The Doctor warns her that unless they can get the creature back into the portal and close it, more of its kind will escape and consume the sun and all the stars in the universe.

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Wikipedia