“Control here. This is a Code Blue call for Agent CANDID.”

Oh fuck. I look round, see Mo looming over me with sleep-disordered hair, violin case in hand. “It’s for you,” I say, and pass her the phone. We squeeze past each other, and I go back up the hall staircase, shivering in the late-night chill as she takes the call.

“CANDID here,” she says.

I go back to the bedroom and pull her go-bag from the closet. What else? Ah, yes. There’s a spare toilet bag packed and ready to go in the bathroom: I fetch that, too, and carry it downstairs. She’s still on the phone, listening intently, as I squeeze past her to the kitchen, plant the bags, then start prepping the coffee maker. Either she’ll have time for a mug before they pick her up, or I can use it in a few hours’ time: it all depends what kind of job it is.

This happens every month or two. Usually she’s gone for a couple of days, sometimes only for a few hours, but on one notable occasion she disappeared for nearly a month. It’s not her they need so much as her bone-white violin and its human attendant. (I hate that fucking thing.) It’s an Erich Zahn original, one of a double-handful fabricated in Weimar Germany. You can’t get the materials to make any more of them, and you wouldn’t want to unless you were a particularly macabre serial killer. The reason the organization needs it is summed up in the now-tattered sticker Mo added to the case several years ago: THIS MACHINE KILLS DEMONS. But to do that, it needs a violinist. And she’s very proficient. Too proficient: if she was less good at it they’d take the thing away from her and give it to some other poor bastard who I wasn’t married to.

Presently I hear the clatter of her hanging up. “Got time for coffee?” I ask as her footsteps come closer.

“I think so,” she says, and I flick the switch on the filter machine. “They’ve booked me onto a six o’clock flight out of London City, but there’s plenty of time. Hand luggage only.” It’s dark in the kitchen, and she’s as pale as a ghost in the twilight glow of the LEDs on the microwave oven. “Speaking of which.”

“I got your bag,” I say as the coffee begins to burble and spit.

“Oh, Bob.” She puts the violin case down on the table, then comes towards me. We embrace awkwardly. She rests her chin on my shoulder. There’s an unpleasant tension in the back of her neck. “I’d better get dressed soon.” She makes no move to pull away.

“Can you say where you’re going? Or how long you’ll be?”