“He beat a man,” he repeats, no weight in his voice. “Very good. Thoughtful of him. This way we can spend Christmas together.”

It takes Thomas a heartbeat to react. A transformation in his Smoke, a lightening, colour entering the grey; a parcel of emotions exhaled by one boy and inhaled by the other; infection: the sharing of a burden.

“Prick!” Thomas says softly, shaping a Smoke ring with his mouth.

“You’re welcome.”

Charlie waits until both their breaths have slowed and Thomas’s Smoke has cleared out of his blood. It’s like stepping inside after racing through a tempest; as such not without a sense of loss. Then he changes the subject.

“Where were you all day? I was looking for you.”

It does something for Thomas, this question, completes his transition from desolation to wry humour.

“Well, first I had to see Renfrew. Kept me for a full three hours. And then I went over to Foybles’s rooms to ask him whether he would help me with my maths.” Amusement flashes in Thomas’s eyes. “Made him rather nervous, I think. The demon boy coming to visit.”

“Maths? But you are doing fine with—”

In answer Thomas opens his right hand which has been curled into a fist from the moment they left the dormitory. Inside sit two little cubes, clear like icicles. For two heartbeats Charlie does not know what they are. Then it dawns on him and his stomach contracts with excitement and fear.

“He will know who took them,” he whispers.

“Maybe. There were five pieces left. He may not know the count.”

“He’s sure to.”

Charlie pictures it, Thomas searching the desk in Foybles’s office, while the latter had his back turned. It seems impossible. Thomas picks the thought off Charlie’s face.

And dares a smile.

“Foybles left me alone in his living room. The question I asked, it turned out to be rather complicated. He needed to consult his books. It appears Foybles has his library under his bed. At least that’s what it sounded like. Like he was moving all his furniture about. Hunting for Newton. He left me alone for a full half hour.” Thomas shakes his head in disbelief.

“Did you smoke?”

“A little. But I opened the window. By the time he came back, it was barely noticeable. And he was very focussed on the problem.”

Charlie tries not to think it. Thief. But there is admiration in the word, too. It has long been a puzzle to him how often sin aligns with pluck.

“Shall we?” Thomas asks. “Together?”

They each pick up a sweet. Held up to the light Charlie discovers a pattern stamped into one side. “B&S” underneath a stylised crown. The Queen’s stamp.

There is no smell to the little cube.

“Let’s do it then. On three.”