Next, Professor Playfair gathered them around and empty worktable for a demonstration. ‘Now, the common man thinks that silver-working is equivalent to sorcery.’ He rolled his sleeves up to his elbows as he spoke, shouting so they could hear him over the din. ‘They think that the power of the bars lies in the silver itself, that silver is some inherently magical substance which contains the power to alter the world.’

He unlocked the left drawer and pulled out a blank silver bar. ‘They’re not wholly wrong. There is indeed something special about silver that makes it an ideal vehicle for what we do. I like to think that it was blessed by the gods – it’s refined with mercury, after all, and Mercury is the messenger god, no? Mercury, Hermes. Does silver not then have an inextricable link to hermeneutics? But let’s not get too romantic. No, the power of the bar lies in words. More specifically, the stuff of language that words are incapable of expressing – the stuff that gets lost when we move between one language and another. The silver catches what’s lost and manifests it into being.’

He glanced up, took in their baffled faces. ‘You have questions. Don’t worry. You won’t start working with silver until near the end of your third year. You’ll have plenty of time to catch up on the relevant theory before then. What matters now is that you understand the magnitude of what we do here.’ He reached for an engraving pen. ‘Which is, of course, the casting of spells.’

He began carving a word into one end of the bar. ‘I’m just showing you a simple one. The effect will be quite subtle, but see if you feel it.’

He finished writing on that end, then held it up to show them. ‘Heimlich. German for the secret and clandestine, which is how I’ll translate it to English. But heimlich means more than just secrets. We derive heimlich from a Proto-Germanic word that means “home”. Put together this constellation of meaning, and what do you get? something like the secret, private feeling you get from being somewhere you belong, secluded from the outside world.’

As he spoke, he wrote the word clandestine on the flip side of the bar. The moment he finished, the silver began to vibrate.

‘Heimlich,’ he said. ‘Clandestine.’

Once again Robin heard a singing without a source, an inhuman voice from nowhere.

The world shifted. Something bound them – some intangible barrier blurred the air around them, drowned out the surrounding noise, made it feel as though they were the only ones on a floor they knew was crowded with scholars. They were safe here. They were alone. This was their tower, their refuge.

They were no strangers to this magic. They had all seen silver-work in effect before; in England it was impossible to avoid. But it was one thing to know the bars could work, that silver-work was simply the foundation of a functioning, advanced society. It was another thing to witness with their own eyes the warping of reality, the way words seized what no words could describe and invoked a physical effect that should not be.

Victoire had her hand to her mouth. Letty was breathing hard. Ramy blinked very rapidly, as if trying to hold back tears.

And Robin, watching the still quivering bar, saw clearly now that it was all worth it. The loneliness, the beatings, the long and aching hours of study, the ingesting of languages like bitter tonic so that he could one day do this – it was all worth it.