The little boy pulled up his flannel shorts. His legs were pale and knobby-kneed. He had not been affected by the banishment. “Hello,” Walden said, before remembering that no one had greeted people that way before the invention of the telephone. “I mean—good evening.”

No reply. The child started walking away from her.

“Wait!” Walden said, and took a few steps after it.

They seemed to have been steps in time. The boy grew into adulthood before her eyes. His hair was turning grey by the time Walden recognised him from the oil portrait hanging in the school hall. He was the doomed Headmaster from 1926. “Mr Merringham?” she tried. “Rodney Merringham?”

“They sent a witch?” said Merringham. “I beg your pardon; a lady magician.” The correction was one that would have mattered a great deal in the 1920s, Walden seemed to remember. The contemporary definition of ‘witch’ varied depending on who you asked: possibilities included the straightforwardly sexist ‘female magical criminal,’ the fairly disrespectful ‘non-academic practitioner’—by that definition, Kenning was a witch, though Walden would never have used the word that way—and of course the defiant ‘academic magician with strong feminist views.’ Roz had called herself a witch for a while. Walden herself had never really got on with the term.

Merringham was peering anxiously at Walden through gold-rimmed spectacles. He wore a black academic gown over a threadbare suit. His voice had had a blurred and distant quality, like listening to a poor-quality recording from long ago. “I need to get up to the tower,” Walden said, watching him carefully. This one, she thought, was a ghost. Merringham had been dead for a century. But some part of him lingered, imprinted in the magic of the demonic plane where he’d died.

“We can’t have it threatening our boys,” Merringham said.

“Indeed not. The tower, Mr Merringham?”

“Death, the Fool, the Ten of Swords, the Tower. A poor prospect, very poor. But we can’t have it threatening our boys.”

Divination, once held to be the fourth arcane discipline—invocation, evocation, instantiation, divination—was totally discredited; a dead science, like its kinsman astrology. Even a century ago it had been on its last legs. “Please, Mr Merringham,” Walden said, “do you know the way up?”

Something in her tone made him frown. “Women,” he said, “are too emotional to truly master magic. It is essentially a manly pursuit—like cricket.”

Absolutely no point having an outdated argument with a confused ghost. “I’m sure you’re right, Mr Merringham,” said Walden. “There’s a boy trapped in the tower. How do we get up there?”

That got the ghost’s attention. “Can’t have it threatening our boys,” he said again. Ghosts were not Walden’s area at all, but she rather thought he was stuck on that idea, skipping and repeating like the ancient recording he resembled. “This way, young lady.”