The invitation isn't yours. Someone across the room already knows.

The ballroom is brighter than the invitation led you to expect — a thousand candles in chandeliers, doubled again in the tall windows. The card is still tucked inside your jacket, as though you might have to produce it again at any moment. The name on it is not yours. The woman at the door barely glanced at it before waving you through.

"At midnight," a footman near the entrance tells no one in particular, "everyone unmasks." Until then, each of you stays whoever you claim to be.

You keep to the edge of the room, where the light is thinnest, counting faces you don't recognise — which is nearly all of them. Somewhere in this hall someone is wearing the real version of the name on your card, and you have no idea what they look like, or when they'll arrive.

Across the room a figure in silver stands half in the shadow of a column. The mask covers the upper half of the face, unremarkable among a hundred others — until a hand rises and lifts the lower edge, just far enough to reveal a mouth, a chin, and above them eyes fixed precisely on you.

It lasts a second too long to be an accident.

The hand lowers the mask again, slowly, without breaking your gaze. The music shifts into a new dance; couples reassemble across the floor. Somewhere behind you, someone calls a name across the room — the name printed on your card.

You cross the floor before you can talk yourself out of it, threading between turning couples who never notice you. The figure in silver doesn't move from the column. Waiting, it seems, exactly where you last saw them.

Up close the mask is finer than it looked from across the room — real hammered silver, worked by hand at the edges, with a thin crack above the left brow that isn't part of the pattern. As if it has already survived an evening like this one.

"You're standing in the shadows," you say, for lack of anything cleverer.

"I'm standing exactly where you see best without being seen." The voice is lower than you expected, amused in a way that isn't aimed at you. "You're new here."

"How can you tell?"

"Because you've been searching the whole room instead of dancing." A pause. "And because I've never seen you before — and I know almost every face here, even under a mask."

The word almost sits between you like an open door.

A call goes up from the far side of the room, bright and excited, a name passing from mouth to mouth. The footman by the door raises a hand. "Our host asks for your attention — the unveiling has been moved up, one hour before midnight."

One hour. Not until dawn, the way you'd hoped. The figure in silver looks at you as though doing exactly the same arithmetic you are.

"I need to tell you something," you say, the words coming out faster than you planned. "The name on my card isn't mine. I don't even know whose it is."

You expect her to step back. Instead she goes quiet, in a way that isn't alarm.

"You know," she says at last, "I've spent this whole conversation trying to work out how to say this without it sounding ridiculous. The name on my card isn't mine either."

For a moment you just stand there, between the music and the murmur of the room, while the truth settles.

"My sister was supposed to be here tonight," she says. "She didn't want to come. I did. So I took her name and walked in before anyone could ask why."

"And if someone recognises you?"

"Then I say I'm her, for as long as that lasts." She tilts her head. "What's your reason?"

Before you can answer, a murmur moves through the room — the host climbs onto a small platform, glass in hand, ready to make an announcement. Behind him, just arrived, stands a woman in blue, scanning the crowd as though looking for someone wearing her name.

"That," the figure in silver says quietly, "might be your answer, before you have to give one."

She takes your hand. "Come with me."

The terrace door closes behind you, and in an instant the music becomes nothing more than a muffled hum through the glass. Outside, the air is cool enough to see your breath, and the garden lies still under a half-moon that gives barely enough light to make out the gravel paths.

She lets go of your hand, steps to the balustrade, and looks back at the lit windows, where shadows are moving — the host, presumably, mid-announcement, though neither of you can hear a word of it now.

"In there, someone is looking for two people who don't actually exist," she says, half to you, half to herself.

"So what now?"

She turns to face you. From here, without the chandelier behind her, you can see the colour of her eyes for the first time — dark, attentive — and, up close, the fine crack in the mask above her left brow.

"At midnight the masks come off," she says. "Whether we're inside or not."

Her hand rises, hesitates a moment in the air between you, and then finds the narrow silver ribbon holding the mask at the back of her head.

From inside, muffled by the glass, a clock begins to strike.

She stops, fingers still on the ribbon, and looks at you as though waiting for something — your answer, your hand, a word that hasn't been said yet.