The culvert came up under the postern in the dark, the way Korrin had been told it would, and he heard it before he saw the water.
He had been standing at the postern door for three hours with a lantern that had no gilt on it and four of the Hard Hands at his back. The door itself was low, an oak slab bound in iron, the height of a man’s shoulder and barely the width of two. It had a bar as thick as his wrist that had rusted into its brackets and a crack down the middle where the damp had got in and worked the grain. Korrin had put his palm flat on the crack at dusk and felt the wood move under it, very faintly, like the flank of a sleeping horse.
Now the water spoke.
It was not a loud sound. It was a long low seething, somewhere under the stone of the eastern wall, like a kettle that has been left on the hob and has forgotten what it was for. Then came a knock. Then another. The knocks were regular, one every three breaths, and they came from below the postern’s threshold, from the black water of the culvert where the Hasp sappers had been digging since the second watch.
