Madame Rossini swung around to us. “Zat green thing from yesterday?” One of her eyebrows shot up.

“He … he means the sea-green coat with the emerald clasps,” I said quickly.

“Yes, and the rest of the stuff that goes with it.” Gideon smiled. “Can’t get any greener than that.”

“Ze stuff! Pearls before swine!” Madame Rossini flung her hands up in the air, but she was smiling. “Alors, ze late eighteenth century for zis leetle rebel. Zen we must dress my leetle swan-necked beauty to go with ’im. I am afraid zere is no green ball dress from zat period—”

“The period doesn’t matter, Madame Rossini. The people at that party won’t know the first thing about historical periods.”

“Just so long as the dress looks old, and it’s long, with a full skirt,” added Lesley.

“Bien sûr, if zat is so,” said Madame Rossini, reluctantly. Lesley and I followed her right across the room like puppies following the lure of a bone. Gideon disappeared among the racks of clothes, while Raphael tried on more ladies’ hats.

“Over there I ’ave a dream of a dress, shimmering green taffeta and tulle, 1865,” said Madame Rossini, twinkling at us. With her tiny eyes and lack of neck, she always looked a little like a tortoise. “Ze color would go well with zat leetle rebel’s green coat. For ze period, ’owever, ze style would be all wrong, as if Casanova were taking Queen Alexandra to a ball in ’er youth, if you see what I mean.”

“Like I said, the guests at this evening’s party won’t know a thing about such details,” I said, holding my breath as Madame Rossini took the Queen Alexandra dress off the rail where it hung. It really was dreamy.

“Well, it certainly has a full skirt!” Lesley laughed. “Turn around in that, and you’ll sweep the entire cold buffet onto the floor.”

“Try it on, my swan-necked beauty! Zere is a tiara to go with it. And now for you.” Madame Rossini took Lesley’s arm and led her to the next row of dresses. “We ’ave ’ere French and Italian haute couture of ze last century. Green was not ze fashionable color zen, but we will find you somezing, never fear.”

Lesley was going to say something, but she choked with excitement at the words haute couture and had a fit of coughing.

“May I try on these weird knee breeches?” called Raphael from behind us.

“Of course, but be careful with ze buttons.”

Unobtrusively, I was keeping an eye open for Gideon. He already had a couple of garments hanging on his arm, and he smiled at me over the top of the clothes racks.

Madame Rossini didn’t notice him plundering her stocks. She happily walked along the haute couture rails, with Lesley close behind her, breathing heavily.

“For cette petite with ’er freckles, maybe—”

“This one!” Lesley interrupted her. “Please! It’s so beautiful!”

“Mais, ma chérie, it is not green!” said Madame Rossini.

“Well, it’s almost green!” Lesley looked as if she’d burst into tears with disappointment right away.

“No, it ees ice-blue!” said Madame Rossini firmly. “Grace Kelly wore it to a gala when Ze Country Girl ’ad won a prize. Not zis precise dress, bien sûr, but it is an exact copy.”

“It’s the loveliest dress I ever saw,” whispered Lesley.

“It does have something kind of green about it,” I said, trying to support her. “Or at least turquoise, with a touch of green. If the light is a little yellowish, it practically is green.”

“Hm.” Madame Rossini sounded undecided.

I looked around for Gideon. He was quietly making for the door.

“I expect it wouldn’t fit me, anyway,” murmured Lesley.

“I zink it would!” Madame Rossini looked Lesley up and down, and then gazed thoughtfully into the distance. “You young girls all ’ave such wonderful leetle waists. Zut alors!” Suddenly she looked fierce. “Young man, where are you going with zose clothes?”

“I … er…,” stammered Gideon, taken by surprise. He’d almost reached the door.

The tortoise turned into a raging elephant breaking through jungle undergrowth. Madame Rossini was beside Gideon in an instant. I’d never have thought she could move so fast. “What is zis?” She tore the garments out of his hand, and her French accent got the better of her. “Were you going to steal zese zings from me?”

“No, of course not, Madame Rossini. I just wanted to … er … borrow them.” Gideon looked as remorseful as he could, but it didn’t work with Madame Rossini. She held the clothes up and examined them.

“Why ’ave you chosen zese, you impossible boy? Zey are not even green!”

I came to Gideon’s aid. “Please don’t be cross with us. We need to borrow them for … for an expedition to the year 1912.” I hesitated for a moment, and then decided to stake everything on a single card. “A secret expedition, Madame Rossini.”

“Secret? To ze year 1912!” repeated Madame Rossini, clutching the garments to her like Caroline clutching her crochet pig. “In zese zings? Is zis a joke?” I’d never seen her so angry before. “This. Is. A. Gentleman’s. Suit. From. Ze. Year. 1932,” she said menacingly, gasping indignantly for air between each word. “And zis dress belonged to a cigar girl! If you went out in the street in zese zings in 1912, zere would be uproar! A riot!” She put her hands on her hips. “’Ave you learnt nothing from me, young man? What do I always say zese costumes are about? Zey are about…”

“Authenticity.” Gideon sheepishly supplied the word.

“Précisément!” Madame Rossini bared her teeth. “If you ’ave plans for a secret visit to ze year 1912, zen not in zese clothes! You might as well land in ze city in a spaceship—zat would be just as discreet!” Her eyes were still flashing angrily as she looked from Gideon to me and back again, but all at once, she started moving and, under our startled gaze, navigated from one rail of clothes to another. A little later, she came back with an armful of clothes and peculiar hats.

“Bien,” she said in a voice that told us she wasn’t going to accept any protests. “Let zis be a lesson to you not to go be’ind Madame Rossini’s back.” She held the clothes out to us, and suddenly her face changed. It was like the sun coming out after dark rain clouds. “And if I find out zat zis wicked boy ’as not been wearing ’is ’at again,” she said, wagging her finger at Gideon, “zen I will ’ave to tell your uncle about zis secret outing!”

I smiled with relief and gave her a big hug. “Oh, you really are a darling, Madame Rossini!”

* * *

CAROLINE AND NICK were sitting on the sofa in the sewing room. They looked surprised when Gideon and I came quietly through the door. But while a beaming smile spread over Caroline’s face, Nick seemed rather embarrassed.

“I thought you were both at that party,” said my little brother. I wasn’t sure which bothered him most, being found watching a kids’ film with his little sister, or the fact that they were both already in their pajamas, and the pajamas, a Christmas present from Aunt Maddy, had hoods with rabbit ears. Like Aunt Maddy, I thought that was cute, but when you’re twelve, maybe it seems different. Especially when you get unexpected visitors and your big sister’s boyfriend is wearing a mega-cool leather jacket.

“Charlotte left half an hour ago,” Nick explained. “Aunt Glenda was fussing around her like a mother hen who’s just laid an egg. Yuck, no, do stop all that kissing stuff, Gwenny. You’re as bad as Mum was just now. Why are you two here, anyway?”

“We’re going on to the party later,” said Gideon, sitting down on the sofa beside him.

“Sure,” said Xemerius, who was lounging about on a stack of old Homes & Gardens magazines. “The really cool guys always arrive last.”

Caroline was gazing adoringly at Gideon with big saucer eyes. “Have you met Margaret?” She had been holding her crochet pig on her lap, and now she offered it to him. “You can stroke her if you like.”

Gideon obediently patted the pig’s back. “Lovely and soft.” Then he glanced at the screen with apparent interest. “Oh, looks like you’ve already reached the bit where the paint gun explodes. That’s my favorite part.”

Nick gave him a suspicious sidelong glance. “You know Tinker Bell?”

“I think her ideas are really cool,” claimed Gideon.

“Me too,” said Xemerius. “Only her hairstyle is … well, the pits.”

Caroline sighed amorously. “You’re so nice! Will you be visiting us often?”

“I’m afraid so, yes,” said Xemerius.

“I hope so, yes,” said Gideon, and our eyes met. I couldn’t suppress an amorous sigh of my own. After our successful visit to the costume stockroom, we’d also made a little side trip to Dr. White’s treatment room, and while Gideon was providing himself with a couple of instruments there, I suddenly had an idea.

“While we’re burgling this place anyway, could you find a kit for a smallpox vaccination that we can take with us?”

“Don’t worry—you’ll have been inoculated against all the diseases you could meet while traveling in time,” Gideon had reassured me. “Including the variola virus, of course.”

“It’s not for me—it’s for a friend,” I’d told him. “Please! I’ll explain later.”

Gideon had raised an eyebrow, but he opened Dr. White’s medication cupboard without comment, and after a little searching, he found a red box and put it in his pocket.

I loved him all the more for not asking questions.

“You look as if you were about to start drooling,” said Xemerius, bringing me back to reality.

I fished the key of the door leading up to the roof out of its hiding place in the sugar bowl in the cupboard. “How long has Mum been in the bathroom?” I asked Nick and Caroline.

“Quarter of an hour at the most.” Nick was looking far more relaxed now. “She was kind of odd this evening. Kept on kissing us and sighing. She didn’t stop until Mr. Bernard brought her a whisky.”

“Only quarter of an hour? Then we ought to have plenty of time. But if she does happen to come out earlier than anyone expects, please don’t tell her we’re up on the roof.”

“Okay,” said Nick, while Xemerius chanted his silly song about necking in the porch again.

I glanced mockingly at Gideon. “If you can tear yourself away from Tinker Bell, let’s get going.”

“Luckily, I know how the film ends.” Gideon reached for his backpack and picked it up.

“See you soon,” Caroline breathed.

“Yup, see you soon. I’d rather watch fairies at work than you two smooching,” said Xemerius. “A demon has his pride, you know. I wouldn’t like anyone to say I was a Peeping Tom.”