The questing knights ride into Cornwall, a proud, unconquered land hostile to Camelot. They camp on a turquoise coast, debating whether Arthur will truly return from Avalon. Sir Scipio, recovered and prickly, doubts; Bedivere insists Britain's need will bring Arthur back. At a headland, Cornish guards demand a tariff-chit and direct Collum down to a stone barn to acquire a travel pass.

Collum descends alone and finds the barn contains an impossible vast garden tended by a tiny old man at a well of black ink. Frustrated by circular bureaucratic runarounds, Collum smashes a porcelain pot to forge a fake chit and storms back up the hill—only to find his companions vanished. Wet and despairing, he stumbles into a tavern, sets the counterfeit chit down, and a barmaid with auburn hair—the same woman from the inn near Camelot—serves him ink and welcomes him to the Otherworld.

The tavern unfolds into open sky and a river, the floor becoming a raft. The woman reveals herself as Morgan le Fay, Queen, and tells Collum the Round Table knight he seeks is in the Otherworld; he must search for him. She vanishes amid bees. Drifting downriver, Collum encounters a lost Roman legion (the Twentieth Valeria Victrix) still trying to warn Eboracum of the Picts, and Sir Ganadal of the Cold Hills, a Grail-quester driven half-mad, whose sword is fused to his hand. Collum tells Ganadal the Grail was found at Corbenic; despairing, Ganadal's horse slips and he drowns in his armor.

The river carries Collum into a half-drowned fairy city built atop aqueducts, where he glimpses Bedivere, Dinadan, and Scipio battling three bizarre fairy knights, narrated by Morgan's disembodied voice in cryptic terms. Collum leaps from the raft to join them but falls short and sinks. Trying to pry up an iron-ringed stone in the aqueduct floor, he feels a strange power stir within him before his strength fails.

A giant plucks him from the water and sets him gently down before walking off in lonely dignity. Collum realizes he has lost his stepfather's sword in the canal and fears he is becoming another lost Otherworld soul. Refusing that fate, he forces himself up and crosses a plaza toward an astonishing sight: a castle made entirely of glass.