[S10E10] The Eaters Of Light

In the present day, in the Devil's Cairn, Scotland, a little girl named Judy goes to a slope against her brother's warnings saying that she wants to hear the music. He tells her that there are ghosts there and that if she stays there, they will eat her. As they go back to the village, Judy turns and goes back to the hill, while a crow alights on a stone, saying "Doc-tor! Doc-tor! Doc-tor!, Doc-tor!", as a carving of the TARDIS is seen on a rock.

[S10E10] The Eaters of Light

Elsewhere, the Doctor tells Nardole to look for some kind of obvious sign of the Romans presence - burning huts, slaughters locals, sweetie wrappers... As they walk Nardole hears a crow say "Dark" repeatedly; the Doctor tells him all crows can talk but are in a mass sulk in the future because humans don't have intelligent conversations with them anymore. He explains they are hurrying because the crow is warning them of danger; they don't have a lot of daylight left. They arrive at a stone camp, which the Doctor explains was built under the ground but close to the sky out of a belief that they are doors between worlds. Calling it an Iron Age church, the Doctor explains that a human settlement must be nearby; there's no point in building a place of religious importance otherwise. Nardole complains its damp, to which the Doctor states; "it's Scotland. Its supposed to be damp."

Elsewhere, the Doctor and Nardole find a Roman corpse. However, it is discoloured blue and mushy. The Doctor says the victim's bones disintegrated from a complete lack of sunlight; "death by Scotland." Nardole jokes about the overcast weather. However, the Doctor tells him that this would take decades of lack of exposure to the sun; this happened a short while ago. The most logical solution is that an alien of some kind has arrived on Earth and is either harvesting or eating solar energy. The Doctor questions where the rest of the Ninth Legion could be and walks off to search. Nardole complains about wanting to go back to bed. They come across a battlefield littered with similar corpses and fires still burning; its the Ninth Legion. The Doctor notes that this massacre didn't happen too long ago, meaning whatever killed the Ninth Legion is still nearby; they need to find Bill before whatever did this gets to her first. However, right as they attempt to leave, Picts ambush them and take them hostage.

Once it's nighttime, Bill and the Roman climb out of the pit. Hearing something nearby, the Roman tells her its what slaughtered the Ninth. He reveals a handful of Romans have survived. As they walk off, the Roman reveals they only survived because they ran. The creature nears. The Roman tells her they're underground near the river and to look for a carving. The creature grabs the Roman with tentacles from its mouth and feeds off the sunlight in his body, killing him. It chases after Bill, but she manages to find the cave the Romans are hiding in. She is met by a sword. However, one of the creatures' tentacles lashes her shoulder. The Romans let her in and block the entrance. In a candlelit area, they rest; Bill reveals the death of their comrade, Simon. Bill notices the creature left black slime on her and passes out.

Back at the cairn, Nardole asks if they're looking for Bill. The Doctor tells him that they are looking for maximum danger in the immediate area and walking into it. If she's there, they'll save her; if she's not, she's safe. Nardole rests outside the cairn, while the Doctor goes in and ponders about the gate Kar mentioned; very possibly there's an actual gateway in there. The Pics grab Nardole, telling him that the gate is opening and that the Doctor won't be back. The sun rises; the light enters the cairn and opens a hidden passage with a blue void.

In the cave, Bill is awoken by a Roman named Lucius. He tells her to move into a beam of sunlight coming from a hole in the cave to burn the black slime off. He gives her some food to regain her strength. Bill says she has to leave, despite protests that the beast is still out there.

While searching for Bill with Nardole, the Doctor runs into Kar, who is surprised to see him back from the cairn. He asks if she knew what was in the gate; its a portal between dimensions. Seeing she has no clue, the Doctor dismisses her as nothing more than bluster. Kar reveals its called the eater of light and that each generation a warrior would hold it off. However, it got out and killed the Ninth Legion. Kar says it will die soon because it's weak. The Doctor tells her that other Eaters will come out of the gateway and there's no way she can hold them back, sarcastically asking if she's holding her weapon the right-way-up. Kar refuses the Doctor's help, as a scream rings through the air.

Outside, a new corpse is found, this time it's a Pict girl. The Doctor states that the creature is feeding off the sunlight, hence why it keeps getting darker; there's very little time left to stop it. Kar blames herself; the Doctor realises the beast was released as a desperate effort to kill the Romans. Kar thought it could be fatally wounded as it slaughtered the Ninth. However, all this did was anger the beast; the Doctor tells Kar that she just doomed the world to protect her home.

Back to the Doctor, he's devised a plan. They need to drive the eater of light back into the portal. However, he is confused by why sunlight opens it. Its because the ancestors who originally built the cairn couldn't properly shut the portal; so they sent a warrior in once a generation to keep the beast from getting out. Nardole compares it to venting an oil gush. Seeing Kar sulk, the Doctor tells her to save mourning the dead for old age; the more time she spends wallowing in that thought, the more people are going to die. He inquires about the mirrors on sticks Kar has, learning it poisons light the beat eats. The Doctor tells them they need to lure the best to the gate before sunrise when it's weak.

Back to Bill, she and the Romans move through a passage in the cave; they spent the last few days exploring to find ways to sneak past the beast. They come across a ladder, which Lucius says leads up to the village of the barbarians; voices and light come from above a trapdoor. Lucius asks Bill if she's sure the Doctor is with the barbarians; "basically, he always ends up being boss of the locals," Bill states. Cornelius attempts a walking to the ladder but is eaten by the beast. Bill and the others rush up the ladder as the Eater is preoccupied.

At the cairn, the Doctor sets up the trap, explaining to Bill that a Pict fighting one off for a few minutes buys 60-70 years of peace and then they get replaced; however, human lives get used up too quickly, leaving the possibility of eventual failure. He tells Bill he has a better idea, which she says is the part he never tells her; the Doctor says its usually because he gets interrupted. Bagpipe music plays, annoying Nardole, who finds it worse than jazz. Outside, the beast arrives and runs inside; using the mirrors, light from torches is turned poisonous to the beast, weakening it. The Romans and Picts stab the best to keep it still until sunrise.

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.

Bill leads the surviving legion away from the creature and end up near the cairn, reuniting with the Doctor and Nardole. The Romans and Picts all agree their squabble is childish given the larger threat. The Doctor works out a plan to lure the Eater back to the portal during daylight. Once the creature is trapped, the Doctor tells them someone needs to stay within the portal until the sun extinguishes to prevent the creature from escaping, but as human life spans are too short, he prepares to enter the portal himself, since his Time Lord physiology and regenerative abilities will protect him. Bill objects and knocks him down, while Kar and the remaining Ninth Legion instead sacrifice themselves as a group to stop the creatures, despite the Doctor's objections.

Alasdair Wilkins of The A.V. Club gave the episode a grade of B+, praising veteran writer Rona Munro on her script, and how she "skilfully mixes the political and the personal", specifically on the usage of the Roman army and the complexity of the characters of the soldiers. He stated how the episode felt like a throwback to a different era of the show, given Munro's being the first writer of the classic era to return to write for the modern era. He felt that criticisms of the previous episode applied to this episode as well, in light of the "retro" feel of the episode. Wilkins felt that the episode was "bizarre", in a positive manner, and that it had a "tremendous, distinctive atmosphere".[8]

BROTHER: Judy! Judy what are you doing? Come on! (The little girl runs up the slope to the old stones, including a pair of uprights with a lintel.) JUDY: I want to hear the music. (She puts her ear to the ground.) BROTHER: You're going to get me in trouble. Everyone knows there are ghosts in the hill. JUDY: Wait! You'll hear it in a minute. (He pulls her to her feet.) BROTHER: That's ghosts. If you stay out here listening to ghosts, they will come out of the hill and eat you. JUDY: They won't. BROTHER: They will. And I'll get the blame. Now, come on. (She starts back down the hill to the village, but turns as she reaches a standing stone with carvings on it. Early Scottish-style music plays.) JUDY: I can hear it. (She runs back up the hill.) BROTHER: Judy, no! BAN [OC]: I'll put the story in the stone. BROTHER: Judy! BAN [OC]: Put your name there. (A crow lands on the stone.) CROW: Doc-tor! Doc-tor! Doc-tor! Doc-tor! (The stone's story includes a carving of the Tardis.)[Moorland](The Tardis materialises in the empty moors.) NARDOLE: Oh, where are we now? BILL: Aberdeen, Scotland. 2nd century AD. DOCTOR: You weren't complaining when it was Mars, were you? (Nardole is in a bright orange dressing gown and knitted woollen cap.) NARDOLE: So why is Scotland suddenly more important than guarding the Vault and keeping your sacred oath? DOCTOR: She thinks she knows more about Romans than me. NARDOLE: Oh, well that's explained everything, thank you. BILL: You don't know more about the Ninth Legion than me. You don't. I read the book. I loved the book. I read everything. DOCTOR: They disappeared. BILL: Except they didn't. DOCTOR: They were annihilated in battle. BILL: Then where's the big pile of bodies? Oh, I don't know. DOCTOR: So where's the Ninth Legion? If they'd left, they should still be leaving. Can you see five thousand Roman soldiers marching south? (Nardole shakes his head.) BILL: Down there, by the river. They'd have followed the river. That's what they did. DOCTOR: There's so much that you don't understand about Roman Britain. BILL: I got an A star. NARDOLE: (sotto) Ooo, got an A star. DOCTOR: I've lived in Roman Britain. Governed, farmed, juggled. And speaking as a former Vestal virgin, second class, I can assure you BILL: I bet you there is a Roman legion down there. NARDOLE: Hang on. What, second class? DOCTOR: Fine. You go and check the river. I'll go and find their last battlefield. BILL: Fine. I'll meet you back here with a Roman soldier. (Bill leaves, heading downhill.) NARDOLE: Yeah, but seriously. Second class? DOCTOR: Yeah, it's a long story. Come on.(The Doctor and Nardole head sort of uphill.)[Woods](Something with monochrome vision watches Bill walk through the trees, and growls softly. Bill hears a young woman's voice.) KAR: (sobbing) I honour you, Mother. I honour you. I honour all our dead. (She is putting items into a small fire.) KAR: I honour you, Father. I honour all our dead. I honour you, Mother. I honour you, Father. I honour all our dead. (Knotted red cord goes into the flames. Bill steps on a twig. The young woman sees her, picks up two Roman short swords and screams, then chases Bill back up the slope. Just as she is about to catch her, she trips, then Bill falls down a hole in the ground. Again. Bill looks up to see a nervous Roman soldier pointing his sword at her.) [Moorland]DOCTOR: Five thousand Roman soldiers. Eyes peeled. They must have left some kind of mark on the landscape. Burning huts, slaughtered locals, sweetie wrappers. (Nardole stops to look at the crow on a stone.) CROW: Dark! Dark! Dark! NARDOLE: Doctor. CROW: Dark! Doctor! DOCTOR: Look, a stone cairn. Pictish civilisation. (Okay, not the pile of stones by a path that we think of today, but like Newgrange in County Meath, Ireland. A substantial stone construction on the highest point nearby, facing east.) NARDOLE: The bird! DOCTOR: What about it? NARDOLE: It said dark. DOCTOR: Yes, well, that's why we're hurrying, because there's not much light at this time of day. NARDOLE: But it talked. DOCTOR: Well, of course it did. It's a crow. All crows talk. NARDOLE: They don't talk in the future. DOCTOR: Course they do. Human beings just stopped having intelligent conversations with them. They all took a bit of a huff. NARDOLE: Crows in the future are all in a huff? DOCTOR: Course they are. Haven't you noticed that noise they make? It's like a mass sulk. Come on. The sooner we get there, the sooner we'll know the answer. (More crows arrive.) NARDOLE: Yeah, I know, but DOCTOR: Picts, early Celts, loved stone cairns. They built them under the ground but close to the sky. They think they're doors between worlds. Iron age churches. What do you always find near churches? NARDOLE: Women in hats. DOCTOR: Exactly. Human settlement. (The standing stones marking the ceremonial route up to the Cairn have colour in the carvings.) NARDOLE: It's all a bit damp, though, isn't it? DOCTOR: It's Scotland. It's supposed to be damp.[Pit]BILL: Oh, a Roman soldier. Oh, I wish I'd studied Latin so you could understand me. (This soldier is from Rome's African lands.) SIMON: I understand you. BILL: Sorry, what? SIMON: I understand you. BILL: But you're, you're speaking English. SIMON: What's English? BILL: Er, what you're speaking in. SIMON: You're speaking Latin. BILL: I'm not. SIMON: That's Latin. You just said that in Latin. BILL: Ah! It's the Doctor. Or the Tardis. Or both. Something, telepathic, link. Auto-translate. That's why everyone in space speaks English. SIMON: What on Earth are you talking about? BILL: Oh my God, it even does lip-sync. SIMON: Who are you? BILL: I'm Bill. (He recoils from her proffered handshake.) BILL: Are you from the Ninth Legion? SIMON: Yes. BILL: Yes! Where have you been? SIMON: Don't you know? BILL: Know what? SIMON: Did you see what happened to us?[Moorland](The Doctor is examining what could be a bog body, except it hasn't been submerged in peat for centuries.) DOCTOR: It's as if his bones have disintegrated. NARDOLE: Ooo. What could do that? DOCTOR: A complete and total absence of any kind of sunlight. NARDOLE: Death by Scotland. (He gets a severe Look.) DOCTOR: No. NARDOLE: No. DOCTOR: It should take decades. This happened a short while ago. This is alien. NARDOLE: Right. Good-o. DOCTOR: Question is, where are the rest of them? NARDOLE: (groans) I just want to go back to bed.[Battlefield](Lots of bodies, and camp fires still burning.) DOCTOR: Well, there they are. The Ninth Legion. Great big pile of bodies. It's not always fun to be right. This wasn't long ago. Whatever did it is close by. We need to find Bill. (They turn to see a line of Picts armed with spears and defended by small round shields. Nardole gasps.) BAN: Don't move! Stay where you are SIMON: The Barbarians dug these traps everywhere. (The creature growls.) BILL: What was that? SIMON: It's what slaughtered the Ninth. Can you see it? They attacked us with a, a thing. A monster. BILL: There's nothing here. SIMON: I've got to get back to the others. BILL: You said they were wiped out. SIMON: There are survivors. A handful. I can't leave them. BILL: Course not. SIMON: We found a hiding place. We might still be safe there. (He leads the way through the trees.) BILL: So what was it like, this monster? SIMON: I don't know. We deserted. We were the ones who couldn't face it. Roman soldiers don't run, and we did. BILL: What? (Something big is coming through the undergrowth. It roars. Simon gets in front of Bill and draws his sword.) SIMON: They're underground, by the river. There's a carving of a fish. BILL: Is that it? The monster? (It gallops towards them, then tentacles with luminous rings lash out of its mouth and grab Simon, reeling him in.) BILL: No! (Bill runs downhill, until she sees a fish carved on a flat stone, then heads inside the cave entrance.)[Cavern](Bill crawls along a passage that opens into a cavern, and is greeted by the point of a sword. Again. A tentacle lashes at her neck and she screams. The legionnaire pulls her inside.) LUCIUS: Block the entrance! Quickly, hurry up! (They all throw stones into the opening, then push over a big rock to seal it completely.) THRACIUS: How long will that hold? LUCIUS: Not for long. Now bring her through, where we can have a better look at her. (In the cavern proper, with camp fires lit.) THRACIUS: You do realise the beast now knows where we are? LUCIUS: You're not one of the barbarians. BILL: No. So, you're the Ninth Legion? LUCIUS: We are what's left. VITUS: (another African) Simon should be back. THRACIUS: He was looking for the road. Our route south. Did you see him? BILL: Yeah. THRACIUS: Well, where is he? BILL: I'm sorry. That creature killed him. What is it, that thing? Where did it come from? VITUS: It killed him? BILL: Yeah. He was covered in this, this like, black slime. (And Bill has got some on her neck.) MARCUS: It knows where we are. We'll all die here in the dark. LUCIUS: No one is going to die. (Bill has touched her neck and seen the slime on her fingers. She collapses.) [Round house](In the Pictish village, in the main round house, the Doctor and Nardole are at the centre of a circle of spears and swords.) DOCTOR: Oh, for heaven's sake. How long are you going to keep us here? Couldn't we have seats? What about the Wi-Fi code, how about that? <b