“Bars?” I saw them now, gleaming pillars of silver steel, each as thick as my arm.

The sound of charging feet started up again behind us, maybe fifty yards back. I pushed Snorri away and fumbled for the key. It slipped from my fingers, treacherous as ice, but the thong held it and I caught it again. “Open!” I tapped it against the closest bar and all of them slid back into their recesses, the top half into the ceiling, the bottom into the floor.

I stepped over before they sunk from sight and turned, sharpish, the others following. The shadows spat Cutter John out at a dead sprint. “Close!” I slapped the key against the gleaming circle of a bar, now flush with the floor. I stood, frozen by the sight of that goggle-eyed monster racing toward me. Snorri jerked me back, but not before I saw Cutter John leap for the narrowing gap . . . and miss. He hit with awful force and I swear those bars rang with it.

“Come on.” Snorri dragged me forward.

“The bars will hold him,” I said. I almost believed it.

Fifty yards on the tunnel entered a chamber as big as the new cathedral at Remes. The black tube that had run along the tunnel core continued through the centre of the open space and vanished into a tunnel mouth on the opposite side. Its path took it into the jaws of a vast machine that sat upon the chamber floor fifty feet below us and extended another fifty feet above the point where the black tube passed through it.

Lights set into the ceiling, too bright to look at, lit the chamber from top to bottom as if it were a summer’s day. The air smelled of lightning, and throbbed with the heartbeat of huge engines.

We stood at the edge where the tunnel gave out onto a sheer fall to the floor far below. If there had ever been any supporting rail or stairs they hadn’t been made of such durable material as the bars back along our path or the titanic machine before us, and perhaps now accounted for the brownish stains down the walls and across the floor.

“There’s someone down there.” Hennan pointed.

At the base of the towering block of metal an alcove had been set into the bulk of the machine, an alcove lined with plates of glass all aglow with symbols and squiggles. In the middle of it, from our angle only visible from the shoulders down, stood a man in a white robe or coat of some kind, his back to us.

“He’s not moving,” Kara said.

We watched for a whole minute, or at least they did: I kept looking back in case Cutter John caught us up and pushed us over the edge.

“A statue?” Hennan guessed, stepping to the edge of the drop.

“Or frozen in time, like Taproot in that Builder vault.” Snorri pulled Hennan back.

Far behind us a dull clanging started to sound. “We should get down there and find out,” I said.

“How?” Kara approached the edge less boldly than Hennan, on hands and knees.

“Fly?” I flapped my arms. “We’re wrong-mages now after all!” I willed myself off the ground, lifting my shoulders, standing on tiptoes. Nothing happened save that I was forced to take a stumbling step forward to keep from falling, and was very glad I hadn’t tried closer to the drop. “Why won’t it work?”

“The Builders’ machines must place counter-spells to protect themselves. How else would they still be working after so many years?” Kara leaned head and chest out over the edge. Snorri beat me to the job of holding her legs. “There are rungs set into the stone of the wall, just like in the shaft we came down.”

She inched back, shook her legs free, then spun around to back over the edge, feet questing for the holds. With the strong suspicion that the clanging noise was the bars back along the tunnel surrendering to Cutter John, I slipped over the edge directly behind her.

A minute or so later all four of us stood on the chamber floor, feeling like ants, both in scale and significance. Snorri led the way to the alcove in the base of the machine. The towering silver-steel engine, through which the black core of the Wheel passed, occupied most of the chamber but a good twenty yards stood between the wall of the chamber and the outer skin of the machinery. The thing looked like no engine I’d ever seen. There were no wheels or cogs, no moving parts, but the structure seemed to be built of many sections and various pipes snaked across its surface, meeting and separating in complex patterns. The whole edifice hummed with power—not a comforting hum but an ungentle sound that carried within it unsettling atonal harmonies that could not have come from any human mind.

“It’s that man from the sign.” Hennan walked at Snorri’s side, a large knife that the Viking must have given him ready in his hand.