London, Christmas 1739

London had set itself to rights after the great storm of thirty years earlier, although it had taken several years to find enough tiles to reclad all the roofs and enough bricks to rebuild the chimneys. Now, it was Christmastime, and the city was in full festive mode, even though it was in the grip of one of the coldest winters in living memory.

The Thames had frozen over, and Londoners took the opportunity to hold a Frost Fair. Colourful canvas tents were pitched on the ice selling food and drink, bowling alleys were established in the middle of the river, daring youths tied dogs to carts and held races from the bridge to Blackfriars, and fiddlers and pipers wandered among the crowds, playing popular tunes for a penny a time.

It seemed that the entire population of the city was having fun on the ice. Nevertheless, once dark fell and the revellers returned to their homes and warm fires, two lost urchins were left to huddle together, desperate for warmth and comfort, under the eaves of St Thomas’ Chapel on London Bridge. The youths were thin and poorly clad, their hair black and curly, their complexions swarthy, as if they were coalminer’s children who had made their way down to London to find their fortunes—and failed dismally.

There was no one else about. Everyone was at home and at cheer, and bundled up before warm hearths. Just after midnight, one of the shivering youths opened his eyes, then gasped. “You said you didn’t want us!” he exclaimed.

His brother woke with a start, then trembled as he saw the little black-haired girl standing before them.

“I said no such thing,” said the little girl.

“You did! You did!” said the first.

“Never,” said the girl. “I wouldn’t throw away such as you.”

The second imp looked carefully at the little girl. “Hang on,” he said. “You’re not—”

“No need to speak names,” said the girl. “After all, none of us have them.”

The two imps looked at each other, then simultaneously shrugged their shoulders. True enough.

“Nonetheless,” said the first imp, “you are little Mistress Surprise, aren’t you?”

Now it was the girl’s turn to shrug. “I’ve lived under this bridge for years. Can’t think why no one seems to know I’m here.”

The imps giggled. “Do you want us then? She has grown tired of us.”

The girl pouted as if she wrestled with heavy thoughts. “Well now, I’d hate to have you tell on me. I wouldn’t be Mistress Surprise, would I, if she knew about me?”

The imps giggled some more. “We won’t tell.”

Suddenly the little girl vanished, replaced by a sense of such terrifying oppression that the imps shrieked and huddled down on the ground, their spindly arms over their heads.

“Don’t! Don’t!” they cried. “We won’t tell! We won’t!”

“Good,” said the little girl, now returned to her less threatening aspect. “Be sure you don’t. I can be just as nasty as my sister when the inclination takes me.”

The imps sulked silently for a while, and the little girl let them think about it.

“On the other hand,” she said, “I can be a great deal nicer, too.”

“Why would you want to be nice to us?” said one of the imps.

“Because I am engaged in a project,” said the girl, “and it is getting too big for me to manage by myself. I am in grave need of assistance.”

“And you’d trust us?”

“Trust is not quite the word I’d use…but I do need you, and you can be a help.”

The imps thought about it for several heartbeats.

“Do you have a nice warm room to keep us?” one of them asked hopefully.

“Of course,” said the little girl, “and not far from here, actually.”

She held out her hands and, after a fractional hesitation, the imps rose and each took one of her hands.