Ark hurriedly slid the iron manhole cover back into place. He could feel the boards vibrating. Any moment now, the cover would be ripped from his fingers and he’d be skewered by the guard’s sword.

The voice was closer now, spitting with anger. “You’re in serious trouble!”

Even Mucum, who would happily take on a killer hornet with nothing more than a crosshead screwdriver, was trembling in the darkness.

Suddenly, the pounding on the boards veered away from them. “Get out of those branches, you little twig! Those cherries belong to the King!”

A second, feminine voice piped up. “I say, Gerald, do as the gentleman asks.” There was a pause. “I do apologize for my wayward progeny, Officer.”

“Yeah. Well. Just keep an eye out, madam. Or I could get in trouble.”

“Of course! Gerald, come and make a gesture of contrition to the smart young man!”

“Do I have tooooo?” another voice whined.

Mucum could easily picture the snotty-nosed brat. At any other time, he’d give him a good slap. But as far as he was currently concerned, the boy was their best friend in the whole of Arborium.

The mother was doing her best to reason with the child. “Yes, or Mommykins will be most upset!”

There was a shuffling of feet and then an unconvincing “Sorreee …”

Not far below, Mucum snorted with disbelief. “Thank Diana for rich, spoiled brats!” he muttered as he descended into the darkness, followed by Ark, whose trembling fingers nearly slipped off the rungs.

Within a few yards the vertical shaft hit the main artery serving the castle. Luckily, the engineers who built this underworld had as little desire as the two boys did to splodge through the river of muck. On either side of the lead-lined tunnel, a raised platform provided access as the human waste poured by below. Low-level guide lamps were strung between pools of shadow, fed by natural methane.

“I say!” Mucum drawled, doing his best to imitate the mother’s voice. “Would you think, perhaps, that if we take another left, we might find ourselves under the inner walls of the castle, what, what?”

“Rather!” said Ark, joining in. “I do believe the old fellow might be jolly well right!” Then it would be a simple matter of locating the nearest access hatch. Ark grinned. Despite the fear, he was enjoying himself. They’d come to see the King. Nothing would get in their way!

“What’s that?” Mucum stopped dead and Ark walked straight into him.

Ark could hear the constant drip of stalactites from the ceiling and the occasional blurping noise that the sludge made as it released yet more noxious gases. And then, in the tunnel ahead of them, a scurrying sound. It wasn’t receding, but approaching, fast.

“Oh!” said Ark. “That —”