“Even though I was born on the day worked out by Newton?”

“I’m sorry,” said Mum. “And do stop going on about Sir Isaac Newton. He’s only one of many who have put their minds to this matter. It’s much bigger than you know. Much bigger and much older, much more powerful. And much more dangerous. I wanted to keep you out of it.”

“Out of what?”

Mum sighed. “It was stupid of me. I ought to have known better. Please forgive me.”

“Mum!” My voice almost broke. “I haven’t the faintest idea what you’re talking about.” My confusion and desperation had been growing with every word she said. “All I know is that something is happening to me that shouldn’t happen at all. And it’s … it’s making me a nervous wreck! I have a dizzy fit every few hours, and then I travel back into another time. I don’t know how to stop it.”

“That’s why we’re on our way to see them,” said Mum. I could tell that my desperation hurt her. I’d never seen her look so worried before.

“And they are…?”

“The Guardians,” my mother replied. “A very old secret society, also known as the Lodge of Count Saint-Germain.” She looked out the taxi window. “We’re nearly there.”

“Secret society! You want to take me to one of those weird sect things? Mum!”

“It’s not a sect. But there’s certainly something rather weird about them.” Mum took a deep breath and briefly closed her eyes. “Your grandfather was a member of the Lodge,” she went on. “And his father before him, and so on. Sir Isaac Newton was a member, like Wellington; Klaproth the chemist; von Arneth the historian; Hahnemann, who thought up homeopathy; Charles of Hesse, who knew all about alchemy and astrology; and of course all the de Villiers family, with many, many more. Your grandmother claims that Churchill and Einstein were also members of the Lodge.”

Most of those names meant nothing to me. “But what do they do?”

“That’s … well,” said Mum, “they concern themselves with ancient myths. And with time. And with people like you.”

“Are there more like me, then?”

Mum shook her head. “Only twelve of you in all. And most of them died long ago.”

The taxi stopped and the glass panel went down. Mum handed the driver some banknotes. “Keep the change,” she said.

“But what are we doing here, of all places?” I asked as we stood on the pavement while the taxi moved off again. We’d driven down the Strand until just before Fleet Street. All around us was the noise of the city traffic. Crowds pushed and shoved their way along. The cafés and restaurants opposite were full to bursting, two red double-decker sightseeing buses stood beside the road, and the tourists on the open top decks were taking photographs of the monumental complex of buildings that was the Royal Courts of Justice.

“Among the buildings over there is the way into the Temple precincts.” Mum put my hair back from my face.

I looked the way she was pointing and saw a narrow pedestrian thoroughfare. I couldn’t remember ever having gone along it before.

Mum must have noticed my blank expression. “Didn’t you ever get taken to the Temple from school?” she asked. “Temple Church and the gardens are well worth seeing. And Fountain Court. For my money, it’s the prettiest fountain in the whole city.”

I looked at her furiously. Had she suddenly mutated into a tourist guide?

“Come on, we have to cross the road,” she said, taking my hand. We followed a group of Japanese tourists, all of them with large London street maps held up in front of their faces.

Behind the row of buildings, we were in an entirely different world. Gone was the hurry and bustle of the Strand and Fleet Street. Here, among the majestic, timeless buildings ranged side by side, no gaps between them, peace and quiet suddenly reigned.

I pointed to the tourists. “What are they looking for here? The prettiest fountain in the whole city?”

“They’ve come to see Temple Church,” said my mother, ignoring my tone of annoyance. “Very old, full of myths and legends. The Japanese love all that. And Shakespeare’s Twelfth Night was first performed in Middle Temple Hall.”

We followed the Japanese for a while and then turned left and walked along a paved path running past the buildings and turning several corners. It was almost like being in the country. Birds sang, bees hummed in the well-stocked flower beds, and even the air seemed fresh and clear.

Finally, Mum stopped. “Here we are,” she said.

It was a plain building, and in spite of its immaculate façade and freshly painted window frames, it looked very old. My eyes went to the names on the brass plate, but Mum pushed me through the open door and took me up a flight of stairs to the first floor. Two young women coming down the stairs said a friendly good day.

“Where is this?” I asked.

Mum didn’t reply. She pressed a bell, adjusted her blazer, and pushed her hair back from her face.

“Don’t worry,” she said, and I didn’t know whether she meant me or herself.

The door hummed and opened, and we entered a bright room that looked like a perfectly ordinary office. Filing cabinets, desk, telephone, fax, computer … even the middle-aged blonde behind the desk didn’t look out of the ordinary. Her glasses were a bit alarming, that was all: jet black and with such big rims that the frames hid half her face.

“How can I help you?” she asked. “Oh, it’s you—Miss … Mrs. Montrose?”

“Shepherd,” Mum corrected her. “I married. I don’t use my maiden name anymore.”

“Ah, of course.” The woman smiled. “But you haven’t changed at all. I’d have known you anywhere by your hair.” Her glance fell briefly on me. “Is this your daughter? I expect she takes after her father. How are you…?”

Mum cut her short. “Mrs. Jenkins, I have to speak to my mother and Mr. de Villiers. It’s urgent.”

“I’m afraid your mother and Mr. de Villiers are in a meeting.” Mrs. Jenkins smiled regretfully. “Do you have much—”

Mum interrupted her again. “I want to be at that meeting.”

“Well … that … you know that’s not possible.”

“Then make it possible. Tell them I’m bringing the Ruby.”

“What? But…” Mrs. Jenkins looked from Mum to me and back again.

“Please just do as I say.” I’d never heard my mother sound so determined.

Mrs. Jenkins stood up and came around the desk. She examined me from head to foot, and I felt terrible in my ugly school uniform. I hadn’t washed my hair that morning, and it was just held back in a ponytail by a rubber band. I wasn’t wearing any makeup either. “Are you sure about this?”

“Of course I’m sure. Do you think I’d make some silly joke out of such a thing? Hurry, please. We may not have much time.”

“Well—please wait here.” Mrs. Jenkins turned and disappeared through another door between two shelves of files.

“The Ruby?” I asked.

“Yes,” said Mum. “Each of the time travelers is represented by a gemstone. You’re the Ruby.”

“How do you know?”

“The first pair Opal and Amber are, Agate sings in B flat, the wolf avatar, A duet—solutio!—with Aquamarine. Mighty Emerald next, with lovely Citrine. The Carnelian twins of the Scorpio sign, Number Eight is digestio, her stone is Jade fine. E major’s the key of the Black Tourmaline, Sapphire sings in F major, and bright is her sheen. Then almost at once comes Diamond alone, whose sign of the lion as Leo is known. Projectio! Time flows on, both present and past, Ruby red is the first and is also the last.” Mum looked at me with a rather sad smile. “I still know it off by heart.”

For some reason, her performance gave me goose bumps. It had sounded more like a magic spell than a poem, the kind of thing that wicked witches mutter in films while they stir a cauldron with green vapors rising from it.

“What’s all that supposed to mean?”

“It’s only a memory jingle, thought up by secretive old men to make something complicated sound even more complex,” said Mum. “Twelve numbers, twelve time travelers, twelve gemstones, twelve musical keys, twelve Zodiacal ascendants, twelve steps in the alchemical process of making the philosopher’s stone—”

“Philosopher’s stone? What’s that supposed to—?” I stopped short and sighed. I was tired of asking questions, and every answer left me more confused.

Mum didn’t seem to want to answer me either. She was looking out the window. “Nothing’s changed here, anyway. It’s as if time has stood still.”

“Did you come here a lot when you were younger?”

“My father sometimes brought me with him,” said Mum. “He was a bit more outgoing about it all than my mother. About the secrets too. I liked it here as a child. And then later, when Lucy…” She sighed.

For a while I wondered whether to ask more questions or not, and then my curiosity won out. “Great-aunt Maddy told me Lucy is another time traveler. Is that why she ran away?”

“Yes,” said Mum.

“And where did she run away to?”

“No one knows.” Mum ran her fingers through her hair again. She was obviously worked up. I’d never known her to be so nervous. I’d have felt sorry for her if my own nerves hadn’t been stretched to the breaking point.

We said nothing for a while. Mum looked out the window again.

“So I’m a ruby,” I said. “Those are red, aren’t they?”

Mum nodded.

“And what gemstone is Charlotte?”

“She isn’t one,” said Mum.

“Mum, do I by any chance have a twin sister you forgot to tell me about?”

Mum turned to me and smiled. “No, darling, you don’t.”

“Are you sure?”

“Quite sure. I was there at your birth, wasn’t I?”

I heard footsteps somewhere, quickly coming closer. Mum sat up very straight, breathing deeply. Aunt Glenda came through the doorway with Mrs. Jenkins, and behind her a small, elderly man with a bald patch.

Aunt Glenda looked angry. “Grace! Mrs. Jenkins says you said—”

“It’s true,” said Mum. “And I don’t want to waste Gwyneth’s time convincing you, of all people, of the truth. I want to see Mr. de Villiers at once. Gwyneth has to be read into the chronograph.”

“But that’s completely ridiculous!” Aunt Glenda was almost screeching. “Charlotte has—”

“Not traveled in time yet, right?” Mum turned to the stout little man with the bald patch. “I’m sorry. I know I’ve met you, but I don’t remember your name.”

“George,” he said. “Thomas George. And you are Lady Arista’s younger daughter, Grace. I remember you very well.”