It was a perfectly crisp London morning, as if all the air in the city had been scrubbed clean and hung out to dry. People on their way to school or shopping or work or brunch surged along the footpaths like blood cells through an artery. Many of them relished this time of day, feeling charged by it with a sense of purpose as potent and invigorating as oxygen itself.

But not Grace Kwan.

By the time Grace had descended the steps outside her apartment block in Brixton, she was barely running on time for work and already exhausted after another night of too little sleep. And yet Grace, as she tugged her trench-coat tighter around her small frame and tied back her shoulder-length black hair, could not help stopping short at the sight of a man in vintage driving goggles waving a buzzing, blue-tipped wand over a rack of newspapers.

He didn't look much like a wizard, at least not any kind that Grace had read about, which was quite a few. With his leather jacket, close-cropped hair and strong-featured face, he seemed more likely to throw Harry Potter out of a nightclub than teach him about potions, but he had an air of authority about him that seemed to be warding off any second glances from passers-by.

Grace edged towards him. She wanted one of those newspapers. She got one every week and she was damned if she'd let another part of her morning routine slide today, slightly-scary-street-wizard or not.

She cleared her throat. "Excuse me? Can I get one of those?"

The man turned to look at her. Sunlight refracted strangely off the lenses of his goggles, like it was trying to be three colours at once. The wand stopped buzzing as he raised it out of her way. "Sure. It's a free paper," he said with a Mancunian lilt.

Grace took a paper off the top of the stack and tucked it under her arm. The wizardish man leapt back like he'd caught his finger in a mousetrap.

"Hey! How'd you do that?" He demanded. He lifted the goggles onto his forehead, revealing blue eyes open wide.

What on Earth was he on about? Grace performed some fast mental calculus to work out the safest, vaguest answer she could give without sounding patronising. "Umm. Just a fluke, I suppose?"

The man lowered the goggles over his eyes, buzzed the wand at her a couple of times, then raised the goggles again. Now he looked concerned. "Let me guess," he said slowly. "It's been four weeks since you had a decent night's sleep?"

Grace froze. There was no way he could have told from looking at her - her make-up always covered the circles under her eyes flawlessly. Could he be a stalker? No, even a stalker wouldn't know about the hours she'd spent lying awake in the dark every night for the last month. There was no explanation - or at least, no rational explanation.

Oh God, thought Grace, slightly giddy with panic. He really is a wizard.

The man noticed her reaction and held up an index finger. "Now, hang on," he cautioned, "I'm usually all in favour of running away, but…"

"I have to late, I'm go for work!" Grace blurted, stumbling backwards into the bonnet of a parked van. She spun around as she bounced off and hurried away as fast as her brogues would carry her, for once grateful for a crowd to lose herself in. I'm just going to forget that happened, she promised herself, keeping her eyes down and her shoulders up. I forget things all the time, it'll be easy. All I need to do is never, ever see that man again.