- After Niniane leaves, it's pretty clear that Vortigern means to use Merlin in a pretty nasty way. Merlin feels that sense of death return to the hall.
- Vortigern doesn't see this as going back on his word. He tells Merlin that since he's demon-born, it means that he's not really human. Therefore, they don't have to be nice to him.
- Then Vortigern lays it down for Merlin: he needs his blood to mix into the foundation of his doomed fortress walls. Only then will they stand.
- If Merlin could, he would have eye-rolled Vortigern: clearly, dude has an engineering problem, not a supernatural one.
- Merlin tells Vortigern he should be ashamed of himself. He's turning Wales into a place of superstition instead of one of science and learning.
- Merlin decides to use these people's superstitions against them and tells them that he has the magic powers of his demon father. He can find a better spell to fix the foundations than just using his blood.
- The priests are not okay with this. They need Merlin to die to cover up their inability to tell Vortigern what's wrong with his walls.
- Luckily for Merlin, Vortigern's warriors think it couldn't hurt to let him have a go at finding the problem with the walls.
- In a well-timed comment, Merlin tells Vortigern that his walls will have fallen again because he insists on building "in the dark." He will build in the light. And with that, the sun comes out.
- Everyone's impressed. Merlin leads them all off to the building site to explain what's gone wrong.