She holds up her other hand. Aneeta throws the red board pen she is clutching. A bad throw, but a good catch. Nikki stands up. All unknowing she holds the perfect attention of the other three. She has different selves for every person in this group—dearest-friend, longed-for-beloved, almost-sister—but those selves are all secondary to the one she assumes naturally and without thinking, which is leader.

She wipes the board clean of revision notes with her sleeve, and starts to write out instead the plan that has slowly consumed her evenings over the last several months. She has taken her time and done her research. She does not intend to make the same mistake twice. You have known doctoral candidates less thorough and less careful. The red pen is swapped out for a black to sketch an array, and swapped back to red for annotations. Mathias makes a small sound. Nikki interprets it as a stifled criticism—he is so afraid, Mathias, of criticising anyone—and says, “Yeah, okay. Will can do the drawing, then.”

Will gets up, obedient, and takes the black pen. Nikki is still writing out arcane notation with the red.

Aneeta has taken a seat on a wobbly plastic chair. She does not notice herself shifting her weight, shifting, shifting, making the bad leg creak. May sunlight is streaming through the classroom windows and gleaming off her glasses as she frowns at the whiteboard. In the corridor, a loud giggle suddenly stifled, as two middle schoolers who should not be out of lessons scamper past on some teacher’s errand. Everyone jumps and looks at the door, but no one comes in. No lesson is scheduled in here until after lunch.

Nikki sets the red board pen down on the empty teacher’s desk. Will completes the fourth layer of the array design with a flourish. Four layers, for the size of demon they suspect they are dealing with, representing the groundwork of an exorcism and a banishment. It is not a live array; there is no magic in it yet, and if they actually go through with this, they will need to make it much, much bigger. Which means they need a space to work in, and time. Challenging requirements, for four teenagers three weeks away from public exams, trapped by the rules and constant registration requirements of a boarding school. You could advise them, based on your own experience. You could say, The cricket pavilion in the middle of the night worked well for us.

“Would help if we had a fifth,” says Will after a few moments of silence—awed silence, worried silence, the silence of people who cannot believe their own audacity—“to hold the last point of the pentagram. Are any of the Year Twelves good? Or we could ask someone from Evoke. Harry or somebody.”

“Or,” says Aneeta, abrupt and sharp. The wobbly chair leg goes clunk as she draws herself up straight. “Or…”