"OK, Hammer-hand," he said. "Think I got us a spot. We go along the edge of the drainage ditch over there to where it goes under the wall. Then we got to get down inside it and ease under the guard tower. It comes out in the clear on the other side."
I got out and followed Gaston over broken stones to the ditch. It was almost a creek, and the smell of it was terrible.
Gaston led me along its edge for a hundred yards, until the wall hung over us just beyond the circle of light from the guard tower. I could see a fellow with a burp gun leaning against a post on top of the tower, looking down onto the street inside the wall. There were two large floodlights beside him, unlit.
Gaston leaned close to my ear. "It kind of stinks," he said, "but the wall is pretty rough, so I think we can make it OK."
He slid over the edge, found a foothold, and disappeared. I slid down after him, groping with my foot for a ledge. The wall was crudely laid, with plenty of cracks and projecting stones, but slimy with moss. I groped along, one precarious foot at a time. We passed the place where the light gleamed on the black water below, hugging the shadow. Then we were under the wall, which arched massively over us. The sound of trickling water was louder here.
I tried to see what was going on ahead. Gaston had stopped and was descending. I could barely make out his figure, knee-deep in the malodorous stream. I moved closer. Then I saw the grating. It was made of iron bars, and completely blocked the passage.
I climbed over to the grating, leaned against the rusty iron to ease my arms. The defense system didn't have quite the hole in it we thought it had. Gaston moved around below me, reaching under the surface to try to find a bottom edge. Maybe we could duck under the barrier.
Suddenly I felt myself slipping.
Below me, Gaston hissed a curse, scrabbled upward. My grip was firm, I realized in an instant; it was the grating that was slipping. It dropped another eight inches with a muffled scraping and clank, then stopped. The rusty metal had given under our weight. The corroded ends of the bars had broken off at the left side. There wasn't room to pass, but maybe we could force it a little further.
Gaston braced himself against the wall and heaved. I got into position beside him and added my weight. The frame shifted a little, then stuck.