Nish was drifting in and out of sleep when he heard a curious squelchy plock, like a hammer being whacked into wet dough some distance away. He thought about getting up to see, but weariness overcame him. Surely it was just a frog jumping onto the stone floor.

Plock, plock. His subconscious must have continued to puzzle away at the sounds, for Nish woke with a jerk. It wasn't a frog – it was the sound made by a crossbow bolt embedding itself into a human body.

He shot up, heart pounding, and stumbled to the nearest embrasure. It was growing light outside, the sun's first rays illuminating a layer of mist that blanketed everything below the treetops. Nish looked out and the blood froze in his veins.

There were air-floaters everywhere – no, air-dreadnoughts – gigantic vessels each supported by five airbags, and three or four times the length of Flydd's air-floater. The sides of each vessel were lined with soldiers and at the prows fluttered the silver pennant of the Council of Scrutators. Nish counted nine air-dreadnoughts, then six more from the other side of the chamber. No, seven – a sixteenth hung high above, on watch. Fiz Gorgo was surrounded.

Nish opened his mouth to roar out a warning, but snapped it closed. They'd already shot the sentries and would do the same to him. Besides, no one in Fiz Gorgo would hear him from here. As he ran for the stairs, eye-searing beams lanced out from cartwheel-sized mirrors on the air-dreadnoughts, converging on the secret chambers of the tower below him.

The floor swelled beneath his feet, grew burning hot and the world exploded in his face.