Taran responds to Pryderi’s words in his typical fashion – by jumping up and whipping out his sword. Others do the same. Pryderi’s lords surround him in a circle, swords drawn. Gwydion demands silence. The High King Math tells Pryderi it’s not funny to joke about treachery. Pryderi says he’s neither joking nor a traitor – Arawn will bring peace to Prydain. Gwydion counters that Arawn’s peace is the prison of death and slavery. Pryderi looks around him and says that the cantrev lords deserve what they get, but if everyone surrenders now, Caer Dathyl will be spared. Gwydion tells him to GTFO, and he leaves.
Expecting Pryderi to attack at dawn, the war leaders prepare the fortress for the impending siege. In the morning, they see that Pryderi is preparing to attack with his full host rather than in skirmishes. Gwydion – looking, as always, like a wolf – calls Pryderi arrogant (causing me to chuckle, since that’s my long-held impression of Gwyddie himself). He decides that, rather than wait for the attack, they will go on the offensive.
Taran and Coll lead one troop, Llassar another. Gwydion bids Taran farewell, then rides off to command the larger group of fighters. The battle begins, and a bunch of stuff happens quickly: Taran sees Llonio, Hevydd and Fflewddur each caught up in the fray. Then he sees Pryderi and tries to challenge him, but Pryderi dismisses him scornfully, in a nice upending of the trope of hero-meets-villain on the battlefield. Eilonwy, who was supposed to be confined to the castle, rides by, her hair tucked up under a helmet. A group of warriors surround Taran, and Coll pulls him free, saving his life.
As the sun starts to set, “when the sky itself seemed streaked with blood,” a new threat appears: the Cauldron-Born. Behind them are more of Pryderi’s men, and Taran realizes with dawning horror that this was Pryderi’s plan all along. The deathless warriors slaughter everyone in their path, then use a battering ram to breach the fortress. High King Math stands behind the broken gates, wearing a white wool cloak, his sword in his ancient hand. The Cauldron-Born pause for a moment as if remembering something, then continue mutely on. They slay the high king, and we hear the echoing sound of a hunting horn. Pryderi’s men take Caer Dathyl and raise the red banner of Pryderi and the black banner of Arawn (of course it’s black). And we have to wait until the next chapter to find out the fate of our companions!