“THIS WAY,” ESSA CALLED over her shoulder. “Try not to get bonked by any moving bits of clock as you go.” Rownie followed her, dazed.

It was then that he noticed the masks.

They covered both the upstream and the downstream walls. Rownie saw heroes and ladies, villains and charmers, nursemaids and gentry. He saw animal masks made of fur, feathers, and scaly lizard skins bristling with teeth. Most had been carved out of wood or shaped in plaster, but he also saw masks made of tin and polished copper, gleaming in the lantern light. He saw thin, translucent masks made of beetles’ wings and carapaces, and wild masks made of bright feathers. He saw long-nosed tricksters and ghoulish false faces. Hundreds and hundreds of masks hung from nails by lengths of string, and every one of them seemed to be watching Rownie as he watched them.

Essa led him to an open space and an empty nail on the wall. “Okay, the giant goes there,” she said.

Rownie looked at the nail. It was high up, higher than he could reach. Essa handed him a long pole with a hook on the end. He carefully hooked the giant mask to the pole, lifted it up to the level of the nail, and got it to stay there.

“Good,” Essa said. “The fox goes over there, near the books.” Somehow she managed to point with one hand without dropping everything she carried. “You should be able to find it. The bunks are near the pantry. Feel free to snack before bed, if you’re hungry, but don’t eat too much of the dried fish or Thomas will have an extremely eloquent fit about how we are likely to starve if we ever need to hide out here for months and months—which does happen sometimes.”

She went the opposite way, moving along the upstream wall and hanging up her own masks one by one. Rownie set off toward the bookshelves on the downstream side. He ducked underneath a ratcheting piece of tree-size machinery.

I’m inside the Clock Tower, he said to himself, still astonished. The troupe lives inside the clock. A place he had always known had turned itself inside out and become something mysterious and strange.

Something about this also bothered him and itched at his memory. He couldn’t think of what it might be.

The masks all stared at him with empty eyeholes or painted eyes. Rownie tried to stare back. He was good at staring contests. You had to have a good stare in a household of Grubs. But there were too many masks for him to meet all of their gazes, and he had to look where he was going to avoid being battered about by the tower’s workings. This staring contest could not be won.