They walked through the empty corridors in silence and behind them the strange witchfire fed and fattened and the vast central hall was enveloped in its swift destruction.
The knowledge of Rhiannon guided Carse to the nerve-center of the Veil, to a chamber by the great gate, there to set the controls so that the glimmering web was forever darkened.
They passed out of the citadel and went back down the broken causeway to the quay where the black barge floated.
Then they turned, and looked back, upon the destruction of a city.
They shielded their eyes, for the strange and awful blaze had something in it of the fire of the Sun. It had raced hungrily outward through the sprawling ruins, and made of the central keep a torch that lighted all the sky, blotting out the stars, paling the low moons.
The causeway began to burn, a lengthening tongue of flame between the reeds of the marshland.
Rhiannon raised the squat looped tube again. From it, now, a dim little globule of light not a spark, flew toward the nearing blaze.
And the blaze hesitated, wavered, then began to dull and die.
The witchfire of strange atomic reaction that Rhiannon had triggered he had now damped and killed by some limiting counter-factor whose nature Carse could not dream.
They poled the barge out onto the water as the quivering radiance behind them sank and died. And then the night was dark again and of Caer Dhu there was nothing to be seen but steam.