The last visitors are drifting out of the Grand Horticultural Fair. One by one the lamps come on, the brass band packs away its instruments, and stewards begin chaining the iron gates for the night. Nobody notices the woman in the red scarf. She slips between the folded stalls, past the roped-off fountain, and lets herself into the great glasshouse without knocking.

Inside, the air is warm and green and untidy. Pots of every size crowd the benches, trailing vines loop down from the rafters, and trays of seedlings, each labelled in smudged pencil, wait beside an overturned watering can. At the far end, a dripping tap twists itself shut with a small squeak, though nobody is standing anywhere near it.

Marisol Vane stands at her workbench with her back to the door, unpinning a gold medal from her coat. "You despised every minute of it, didn't you?" she asks, without turning round.

"It is a pleasure to find you in good health, Marisol," the woman in the red scarf replies, brushing pollen from her sleeve.

Marisol turns and holds out a soil-stained hand, which her visitor does not take. Marisol shrugs and flicks her fingers towards the only stool. At once a heap of sacking slides off it by itself and folds neatly into a corner, and a curtain of jasmine draws itself aside to let the visitor pass.

"I cannot pretend to admire such displays," the woman in the red scarf says, inspecting the stool before she sits.

"Neither can I," says Marisol. "Have you seen what wins medals these days? These gardeners" — she says the word as if it tastes sour — "soak their lilies in dye and hold up their roses with hidden wire. They are a row of candles calling themselves sunrises, and I am simply the sun standing quietly among them."

"And yet I found the judges' admiration for you quite mystifying," the woman says. "Your roses were crooked. Your ivy had escaped its frame."

"Can't be too tidy if I want them to believe I grow things the same way everyone else does," Marisol says with a laugh.

Marisol folds her arms. "Your note said you wished to make me an offer."

"So I did," the woman in the red scarf says. "I keep an academy — a quiet school for people whose talents are, let us say, inconvenient. But I did not cross three borders for prize roses. Rumour tells me that the real wonder in this glasshouse is not you at all."

"And rumour is right, for once!" Marisol claps her hands, eyes shining, and calls into the shadows. "Pip! Come out now, please."

A small girl edges out from behind the potting bench, her boots too big and one plait unravelling. She is as still and watchful as an owl on a fence post.

"Pip, this lady has travelled a very long way," Marisol says. "I would like you to show her what you can do with the rose."

The girl's eyes widen. "You promised," she whispers. "Never in front of strangers — you said never, not for anyone."

Marisol's smile fades. She crouches and grips Pip's shoulders, and her voice turns hard. "This visitor is different. This one matters." Then, more gently, she tucks the loose plait behind the girl's ear. "It's all right, sparrow. One time only, I promise."

Pip nods slowly and turns to the workbench, where a rose stands — long dead, brown and brittle, its petals hanging like scraps of burnt paper.

Pip stretches out her fingers towards it. Her knuckles turn white where she grips the edge of the bench. Slowly, the dead stem straightens; a green flush climbs it like water rising, and a single bud creaks open into a deep red bloom.

"Charming," says the woman in the red scarf, sounding bored. "A good forcing-house could manage nearly as much."

Pip does not stop. The rose shivers, then crumbles all at once into a heap of grey dust. The woman raises one eyebrow — and then a new shoot springs up out of the dust itself, climbing and unfolding, until a fresh rose, white as frost, opens where the dead one stood.

"Now that is rather more interesting," says the woman in the red scarf, leaning forward at last.

Marisol looks to her visitor for a reaction. "Well, Ondine?" she says. "Shall we talk about your offer?" Behind them, unnoticed, every seedling in the trays stands a little taller.

Glossary
horticultural: to do with gardens and growing plants
sacking: rough cloth used for making sacks
forcing-house: a heated greenhouse used to make plants flower earlier than usual