Yarn gestures with his left hand — the one without the string — and a barista comes up to the table.

"Two americanos, please," he says, without turning his head.

The barista notes the order and heads back inside. This café isn't meant to have table service.

Yarn reaches under the table and lifts up a brown leather briefcase, putting his string in the inside pocket of his jacket: it's the first time Penny's seen him without it in his hand. He sets the briefcase down on the table and snaps open the seals.

"Tell me," he says in his usual teaching voice, "what can you tell me about a group called 'Factio Umbrata'?"

For a moment, Penny considers playing dumb. She's not sure where the impulse comes from; after all, it's not like she has much to tell. Maybe she just wants a little more control of an unexpected situation.

"I know a little," she admits. "They want to keep ma— the Art a secret. That's really all I know."

Yarn nods, apparently satisfied by this answer.

"What you probably don't know," he says, "is that they have a significant presence… here."

"Here?" Penny echoes.

"On the south coast of England," Yarn clarifies. "And specifically, in this city. We've been monitoring their activities for some time."

Penny notes the word "we"; she suspects she knows what that means.

"You're with the Lucerists," she says. It's not a question.

Yarn smiles. "Well deduced." He opens his briefcase, adding: "More specifically, I work for the DEC, the Department of Enforcement and Compliance."

Penny blinks. "Enforcement and Compliance?" The phrase feels unpleasantly ominous upon her tongue, almost bearing a perceptible flavour in the utterance.

Yarn gives a sort of grimace. "Certain influential policy makers wanted to avoid the word 'police'. But that's essentially what we are. Our job is to ensure that the Art is not used in dangerous or disruptive ways." He takes a folder from the briefcase and lays it down on the table, as the barista from earlier comes to set down two cups of coffee.

"Thank you," he says. Again, he doesn't look.

Penny mumbles her thanks as well. She takes a sip from her cup before remembering she doesn't actually like coffee. Yuck.

Yarn opens the folder on the table, revealing a set of photos, maps and typed notes. Actually, on closer inspection the photos are actually photorealistic pencil sketches. They must have been drawn by someone very skilled. Penny leafs through the documents: they appear to detail the movements of six people, all from different parts of the country, all now within a five mile radius of Penny's home town.

"As you can imagine," says Yarn, "we're somewhat concerned about this sudden confluence. We'd really like to know what they're planning, who the target is and, ideally, how to stop them." He fixes his gaze directly at Penny. It's kind of uncomfortable. "That's where you come in."

Penny stares at Yarn incredulously. "You want me to infiltrate a terrorist group? Are you serious?"

"As a heart attack," he says, his tone stern and measured.

Penny sits silent for a while, trying to form the best way to respond.

"…fuck off," she says, eventually. It's an uncharacteristic level of vehemence, and by far the harshest language she's used with her mentor, but the situation seems to warrant it. "D'you think I want to get killed?"

Yarn sighs heavily, his eyes somewhere just south of a glare. "Look," he retorts, raising a finger, "first of all, you agreed to work for me. You're my apprentice. That was the deal. Secondly," he raises a second finger, "they're not going to hurt a child. That's not their style. Thirdly," he raises a third, "you're far better trained than I was at your age: just look at what you've achieved in such a short time. I'm impressed, really. Finally," he lowers his hand and sighs once more, this time in resignation, "…I wouldn't even think of asking if I had any other options."

Penny's seriously taken aback by this last point, so much so that she almost doesn't notice the rare praise her teacher just gave her. She stares for about half a minute, trying to work out how to play the situation.

"Don't you have anyone else you can ask?" she says, confused. "I mean, you have a whole Department of Reinforcement or whatever."

"Enforcement and Compliance," Yarn corrects. He shakes his head apologetically. "You've seen how people's lives shape their patterns, yes? You can tell intimate details of someone's life just from looking at them, if you know how. Undercover work's nearly impossible in our community: these people can practically smell if someone's from the Department. But you are at a distance from us."

He looks into Penny's eyes, pleading. She's never seen him show vulnerability before.

"It has to be you," he says. "If you don't help, people may die."

Penny pauses for a while. She's not thrilled, but his argument makes sense: she's barely started and she can already see a lot in the pattern. She nods, reluctantly.

"Okay," she says. "What do I need to do?"

Yarn leans back, apparently relieved by this answer. He gives a smile — not a smirk, but an honest-to-god smile — and somehow, he look almost excited.

"First things first," he says, taking something else out of the briefcase, "you'll need a cover glamour." He holds up a white envelope that bulges in the middle.

Penny cocks her head slightly. "What's a cover glamour?"

"Usually, people who go undercover have what's called a 'legend': a fictional identity backed up by passports, driver's licenses, and so on," he explains. "But these people don't care about any of that; they can just look at the pattern, so what we need is for your pattern to look right." He opens the envelope, revealing a smooth, black stone with a hole through the middle. "A cover glamour is an object that's designed to cancel out parts of your pattern you don't want others to see. How are you with mathematics?"

"Um, okay, I think?" Penny replies, confused.

"A cover glamour is like a negative number. You add it, and it's like taking something away."

He hands the stone to Penny; she takes it quietly, gazing at it as though it held the mysteries of the universe.

"I've prepared this stone to act as a cover glamour," he says. "You'll need to work on integrating it into your pattern, but it should erase all traces of me."

Penny nods. "Um, so," she begins uncertainly, "why can't you just do that for someone in the Department? Why do you need me?"

Yarn shakes his head, a glimmer of apology showing on his face. "There's too much to hide. You can cover up individual associations, but not a whole identity."

She nods again. It makes a sort of sense.

"Once it's integrated," he continues, "you must keep it on your person at all times. I suggest wearing it on a string around your neck."

"How do I integrate it?" Penny asks.

Yarn takes his string back out of his pocket, wrapping the string three times around his little finger and once around his thumb.

"Watch," he says, and Penny watches as he takes a reality-fibre from his briefcase and passes it through a loop in his hand. "Just do that a few dozen times: that should be enough to hold for the duration of a meeting."

He undoes his work and puts the string back in his pocket. Then, he takes a business-card-sized item from the briefcase and hands it to Penny. It's a piece of paper bearing an address, date and time.

"That's where the local cell are having their next meeting," he says. He looks her dead in the eye. "Can I trust you, Penny?"

Penny swallows and nods, silently. Yarn's stare is intense, making her feel a little uncomfortable, but at the same time it feels good to be trusted.

"Good," Yarn says. He stands to leave.

Penny pockets the stone and checks the time on her phone. It's 7:10 PM.

"Shit," she says, "I've got to go."

Yarn gives a look of understanding. "Report to me at our next session," he says, and Penny takes off running before she's even finished nodding.

Her mum's going to kill her.

By some miracle, it only takes Penny five minutes to get home, but that still leaves her fifteen minutes past her usual latest acceptable arrival time. She just about remembers to drop her girl-glamour before going into the house — it probably wouldn't do anything to her parents, but it's best to be cautious — and the door closes shut behind her just as her mum comes out of the kitchen.

"Daniel!" her mother exclaims. "I was about to call. Where were you?"

Penny's not prepared to hear that name: for one blissful afternoon she'd gotten used to just being 'Penny'. It takes her a moment to answer.

"I was hanging out with Michelle," she says, which is true; "Studying," she adds, which is half-true; "…and we lost track of time," she finishes, which isn't true at all. She braces for admonition, but it doesn't come. What does come is somehow worse.

"Oh, I see," her mum says with a knowing smile. She sighs. "My little boy is becoming a man."

Penny blushes, which would've been a mistake if she'd had any control over it. Unfortunately, it's just going to strengthen her mother's suspicions.

"Anyway," mum says, mercifully changing the subject, "your dinner's still warm. It's on the table."

Dinner tonight turns out to be spag-bol, which Penny eats about as fast as she thinks she can get away with. She really wants to get upstairs and to her room as fast as she can: the girly clothes in her backpack are precious contraband here, and she's eager to store them somewhere safe. But her mother watches over her to the last mouthful.

"By the way," she says once Penny's put her plate in the dishwasher, "your father and I will be away this weekend. We can trust you on your own, right, Daniel?"

Penny's heart fills with joy at this news: she's not planning anything nefarious, but it's the perfect opportunity to be a girl around the house. Maybe she'll even invite Michelle over.

She nods. "You can trust me, mum," she says, and then she heads up to her room.

Once she's safely in her bedroom, Penny pulls her clothes off as fast as she can. She doesn't want the boy-things to touch her skin any longer than is necessary: it's like they're somehow unclean. She'd like to put on her new girl clothes, but she can't be sure her mum won't come up to check on her, so she puts on a set of pyjamas that're fairly gender-neutral, hiding the girly clothes in the bottom of her wardrobe.

Actually, as boys' pyjamas go they seem downright girly: they're made of a soft blue fabric, chest emblazoned with cartoon characters from a TV series Penny was obsessed with a few years ago. They don't fit as well as they used to, but they're a lot more psychologically comfortable than the dull grey sporty pyjamas she's received more recently.

Who decided pyjamas should be sporty? It's not like you're likely to need to run in them.

Penny sits at her desk and boots her computer. There's a few hours to kill before sleep makes any sense, so she'd better find something to do, something to distract from the girly clothes burning a metaphorical hole in her wardrobe. She fires up a browser and — with appropriate privacy measures — navigates to one of her guilty-pleasure websites, full of stories where rough-and-tumble boys get made over into pretty girls.

She spends the rest of her evening reading those stories. Most of them are pretty badly written, and many contain rather more sex than she'd like. They're comforting, in a way — it's a kind of escapist fantasy, to be turned into a girl by force — but at the same time they concoct a heady brew of arousal and disgust within her. It makes her wonder if maybe she's not really Penny Reed, the girl. Maybe she's just Daniel Reed, the pervert.

Penny Reed, the perverted boy-girl thing, lies herself down on top of her bed, half-falling onto it as she struggles to muster the effort needed for any sort of grace. She makes no attempt to pull the covers over herself: when sleep eventually comes, she's still just lying there on top of her bedsheets, with tears flooding her eyes.