Darla came to lie beside Nona, peering around the chimney and over the roof ridge into the cloister yard.

“How in creation . . .” Darla’s mouth hung open. “The tree . . .”

The centre oak stood decked in green, the thick multitude of its leaves tossed this way and that by the blustery wind. The evening before it had been a stark cluster of sticks, every leaf wrapped tight against the cold.

“It’s called horticulture,” Nona said. “A smelly business.”

“So. When do we do it?”

“Wait.”

They held at the roof ridge, waiting.

“How long for?”

“Not long. Look.” Nona nodded across to the less-used west entrance.

A novice came running through, hair covered by a nun’s headdress, face down, weaving past the first girl in her way.

“Challenge!” Mally gave chase. The novice kept running. “Challenge!”

Crocey surged into the girl’s path and seized her shoulders, shaking her. “She said ‘challenge’ you stupid—” The headdress fell away revealing Jula, nervous and flushed.

“Incorrect challenge. They all miss a meal,” Nona said.

A second novice came in at a run, through the main entrance this time, steering all eyes from Nona’s side of the cloister. Darla started to rise. “Shouldn’t we?”

“Wait.” Nona pulled her down.

Down below Joeli’s shriek cut the air. “It’s a trick!” She raced towards the new intruder. “Check her eyes! Check the eyes!”

The new girl wore a headdress and a scarf bound around her face. She moved like lightning.

“It’s her! It’s her!” Meesha cried as the girl dodged past.

“Challenge! Challenge!” Joeli reached them. “Got you!”

Her triumph proved short-lived. Ruli pulled her scarf aside, grinning beneath eyes that showed no white.

“How?” Darla whispered.

“Blackwort drops. It lasts a day or two,” Nona said. “They all lose another meal.”

A third girl burst from a window in the east range, headdress in place, scarf across her face.

“Wait! Wait!” Joeli screamed. “Let her get in the sun.”

Mystic Class novices closed from all sides. “Watch for a shadow!”

As the new girl broke from the shade of the gallery half a dozen challenges went up as one. “No shadow!” “Challenge!” The girl skidded to a halt. Elani snatched the headdress from her. Golden hair spilled out.

“Lose a meal,” Nona whispered.

“How?” Darla sounded exasperated even though it wasn’t her meals being cut.

“Ara’s great at shadow-work,” Nona said. “She just sucked it up into her eyes making them like mine.” Nona rolled to the side and started to retreat down the slope of the roof. “Get ready.”

Screams went up. It would be the four Red Class novices Nona had recruited. With heads and faces covered they were to rush in after Ara was caught, one from the west entrance, one from the main entrance, one from Ara’s window and the last ten yards behind the first, all of them screaming like banshees and weaving to avoid capture. In the chaos the defenders might not notice how short the decoys were.

Darla stood up and bent over with her back to the chimney and hands cupped almost a yard above the tiles. “This is still insane. You’ll die.”

“In service to the Ancestor, death is but a kiss.” Nona quoted Sister Wheel with a grin, and from the edge of the roof she began to run at Darla with all the speed she could muster.

Nona let the world slow around her even as she accelerated up the slope. The high screaming of the little novices tumbled down the registers. She leapt for Darla, lead foot aimed at her cupped hands. Shoe met fingers and Darla heaved upwards as they’d practised, lifting with all the power of her back, shoulders and arms. Nona bit down on the terrified yell that so badly wanted to escape her and flew through the air, arms pinwheeling.

Below her, struggling through the moment, the novices from Red Class tried to evade the Mystic guards. Perhaps more challenges rang out in the chaos, Nona couldn’t tell. Sister Apple would know. Nobody had seen Apple but they knew she was there, watching.

With their attention on the running novices at the far side of the cloister none of those in the square looked up to see Nona’s flight. The green wall of the centre-oak’s foliage rushed up to greet her, along with a hundred opportunities for being impaled. “I’ve missed! I’ve missed!” Nona could see nothing but leaves. “Ancestor protect me!” She had no time to say the words but they ran behind her lips.

In the next moment Nona was crashing through twigs and greenery. Perhaps she added her screaming to the mix in the cloister. She was too scared to know. The net took her by surprise even though she had been trying to aim for it the whole time. Her arms shot through the holes. The ropes lashed her face. The branches to which she had secured the corners the night before now creaked and groaned in protest, swaying all around her.

For what seemed an age Nona lay entangled in the net’s embrace, panting out the panic that had filled her during the plunge. Gradually she became aware of the shouts and screams in the surrounding cloister, dying away now. Somewhere close at hand Joeli was cursing.

“. . . the bitch. Four wasted challenges.”

“Watch everything! She’ll try again.”

“She’ll be in the next wave!”

“This is cheating!” Joeli again. “She’s supposed to be disguised as other people, not have other people disguised as her!”

Nona lay high in the arms of the great oak, cocooned in green.

This is a stupid game.

Shut up, Keot.

Well it is.

Very slowly, Nona began to untangle herself. The puzzle-box lay where Sister Apple had placed it that morning, low down in a fork of major branches. The leaves that close to the ground were not thick enough to hide her. It sat there, taunting her. A cubic box maybe six inches on a side, a thing of black and white, perhaps a bone body inlaid with ebony, a handful of small locks and catches on each side.

Even if you could get it unnoticed they would see it gone before you had time to open it and then they would just challenge the tree.

I thought you weren’t interested in my silly game?

Keot didn’t reply. But clearly he hadn’t been paying as close attention to Nona’s doings this week as she had imagined. She wondered what else he had to occupy his time.

Nona fished from her habit the box Ruli had fashioned for her. “Damnation.” The impact with the net had splintered one side, breaking away some of the fire-blackened washers that Ruli had used in place of locks. The body was bleached boxwood, the black design painted on with a tarry mix. It bore only a passing resemblance to the puzzle-box below, but if Sister Apple had taught them anything about disguise it was that people saw what they expected to see.

Nona looped her string around the hook at the corner of her fake box then clambered through the branches, keeping high. It took a while and she was thankful for the wind, for without it her passage through the branches would have been betrayed by the localized motion of the leaves.

At last she reached a position five yards above the box where the foliage was still thick enough to conceal her. Anchored by one hand, she used the other to dangle her second string. This one ended in a noose, with a lead fishing weight hung just above the loop; something from the endless mystery of Ruli’s pockets, suggested to stop the string fluttering to the wind’s tune.