“I thought we’d just jump straight back.” Lily rubbed her sore arm crossly. “I didn’t know we’d have to do all this other stuff first. And that injection really hurt.”

Preparing for time travel turned out to be complicated.

After lunch, Oz, Caydon and Lily had been given painful injections for smallpox and bubonic plague. They were then taken to a professor at the Victoria and Albert Museum, who fitted them with real seventeenth-century clothes (the SMU time scientists said anything modern would simply disappear in the past). Silver hadn’t needed the injections, but she joined them for this part, and there was a lot of giggling when the four of them saw what they would be wearing. By now they were all slightly silly with excitement.

The ancient clothes were faded and frayed and smelt of dusty museums. Lily and Silver were given long dresses of thick, dark green woolly material, with huge skirts and stiff tops like corsets. Their hair was bundled away into tight white caps. Oz and Caydon had baggy, knee-length breeches, short jackets and big black hats. They all had to wear withered antique shoes with wooden soles.

“I’m glad nobody from school can see us,” Oz said. “We look like a bunch of scarecrows.”

“Look on the bright side,” Caydon said cheerfully, studying himself in the mirror the professor held up. “At least we’ll blend in. And it’s a lot better than suddenly finding ourselves stark-naked in the middle of history.”

Once they were all kitted out in their mouldy costumes, Silver took them to an SMU shooting gallery in the basement of the MI6 building, where a grey-haired army sergeant issued them with seventeenth-century muskets and showed them how to make antique bullets with little lead balls and gunpowder.

“This takes ages!” Oz complained. “By the time I’ve loaded the gun, I’ll be dead! James Bond wouldn’t get far with one of these.”

“Why can’t we have real guns?” Caydon wanted to know.

The sergeant said modern guns could not be transported back in time, and made them do an hour of target practice. Oz had the best aim, Caydon was the fastest loader – and Lily was so useless that she nearly shot the sergeant.

“I’m rubbish – I’ll never be able to do this!”

“Don’t worry,” Silver said, “I’ll take care of you – I’ve used one of these before.”

Lily did better with the funny little metal device they were given after the shooting lesson.

“This is a tinderbox,” J explained. “Matches weren’t invented in the seventeenth century. A tinderbox makes a spark by striking steel against flint. The spark lights the dry cotton wick, and that makes a flame to start a fire.”

The metal box had a small handle at the side; you pressed it to strike the flint and steel together. Oz couldn’t get a single spark for ages. Caydon managed one spark, which set fire to his breeches. Lily managed to light a pile of dry straw at her first go.

“Excellent,” J said. “I’ll put you in charge of the tinderbox and the boys can have the muskets. And you’ll all be carrying swords, naturally.”

“Swords!” Lily squeaked.

The antique swords came from the Museum of London. The children buckled the leather belts around their waists, and Oz and Caydon practised whisking the blades out of their scabbards like people in a film, until J said, “Don’t use any weapon unless your lives are in danger. Remember that anything you do in the past could have a knock-on effect in the present – look what happened when Demerara spent just a few minutes in the Elizabethan age.”

“I suppose if we killed someone,” Caydon said, “lots of people wouldn’t get born.”

“Precisely. Stay out of sight as much as possible and try not to speak to anyone.” He turned solemnly to Silver. “I don’t need to tell you this will be the hardest job you’ve ever done for the department. Good luck.”

“Thank you, sir.” The seventeenth-century Silver, in her long green dress, stood to attention.

“Good luck, all of you. Remember, your mission is to spoil D33’s plan – and make sure London burns. What you’re doing might seem horrible and cruel, but you mustn’t allow yourselves to weaken.”

Oz said what they’d all been thinking. “But we’ll be killing people.”

“There were six recorded deaths in the Great Fire,” J said. “More deaths went unrecorded, of course – but the numbers were tiny, compared with the thousands who will die if Alba gets her way. Remember that.”

 

A car with darkened windows took the four children through the quiet Sunday city, eastwards along the Thames. They got out beside a tall stone column, with gold flames carved at the top. It was at least as tall as Nelson’s Column in Trafalgar Square.

“It’s called The Monument,” Silver said. “It was designed by Sir Christopher Wren as a memorial of the Great Fire. You can go inside and climb up to the top – I did it in 1888, when I visited with my parents. There are three hundred and eleven steps.”

Oz said, “If we don’t start the fire, this thing won’t exist when we come back.”

The streets around the monument were cordoned off with plastic police tape, and there were groups of armed police on every corner.

One of the policemen came to meet them. “Hi, kids – Rosie said I’d run into you.”

It was their old friend Alan, from the SMU branch of the river police. They had met him during their last adventure, and he was engaged to Rosie from the commando unit. He was a tall, strongly built young man, with very blond hair and pink skin.

Lily hugged him, and he did high fives with Oz and Caydon.

“And this is Silver, our vampire bodyguard,” Lily said.

“Hi, Silver,” Alan said. “Wow, look at you all – you’re like something in an old painting!”

“Don’t rub it in, mate,” Caydon said. “We feel stupid enough.”

Alan chuckled. “Sorry. As you can see we’re right beside the river, so the river police are in charge of this operation – and it’s a good thing this is a Sunday and none of the office workers are here to get in the way. My orders are to take you to the exact site of Pudding Lane, where the Great Fire started. Keep close together, now.”

The buildings here were all brand-new offices, with walls of shining glass. It was very odd to see their tattered seventeenth-century reflections as Alan led them down the deserted narrow streets.

They stopped at a very ordinary modern printing shop. “This is the nearest we could get,” Alan said. “It should bring you within five metres.”

Demerara and Spike were waiting on the desk beside the till. Demerara had a piece of see-through plaster stuck across her mouth and her bright green eyes were boiling with fury.

Lily went to stroke her. “What happened to her mouth?”

“J’s orders,” Spike piped up. “The old girl just can’t seem to remember that she’s forbidden to talk – and a talking cat will get the lot of you burned as witches back in the seventeenth century. So J taped her mouth up to be absolutely sure.”

Demerara quivered. “Mmmmmgh!” she shouted through the strip of plaster.

“Never mind.” Lily tried not to smile at how funny the cat looked. “It won’t be for long.”

“I’m afraid I can’t take it off,” Silver told her. “But I’ll give you an extra conditioning treatment when we get back, and put some lovely pink glitter in your fur.” Silver adored Demerara, and (unlike Lily) never got tired of being her beautician.

“Mmmmgh!” Demerara sounded a little less angry, and allowed Lily to pick her up.

Alan saluted Silver. “Over to you, Major.”

“Wow,” Lily said. “You’re a major?”

Caydon gave a snort of laughter. “No wonder she’s so bossy!”

Lily was about to snap that Silver was only bossy because she was protecting them – but the serious look on Silver’s face stopped her. They didn’t need an argument now.

“Stand in a circle, please,” Silver said quietly. “Spike, get inside Oz’s hat. And Demerara, you can ride on Lily’s shoulders.”

Oz scooped up the rat and stowed him inside his hat – his little feet felt very sharp on his scalp. Demerara draped herself around Lily’s shoulders, like a stout, heavy, furry scarf.

Silver took a small piece of paper from the sleeve of her dress. She unwrapped it carefully; it contained six tiny balls of chocolate. “These are made of the chocolate from the leg of the phoenix. If the time scientist has got his sums right, they’ll keep us in the past for at least three hours. Put one on your tongue and join hands.”

“But what about Demerara?” Lily asked. “Shall I take the tape off her mouth?”

“I’ll do it.” Silver came over and gently peeled away the plaster.

“It’s a disgrace and an OUTRAGE! I will NOT have a dirty great piece of plast— Mmmmmmgh!”

Silver had neatly slipped in the chocolate and sealed her up again.

“Cor, it’s funny when the old girl can’t talk!” Spike poked his head out under the hat to swallow his piece of chocolate. “It’s the first time she’s shut up since the bank holiday in 1973 when she tried to eat a toffee!”

Lily put the little ball of chocolate on her tongue. There was a slight warmth as it melted against the top of her mouth. She grasped the hand of Oz on one side and Silver on the other, and an electric charge of power shot around the circle.

Lily had imagined that going back in time would be like flying. It was more like the earthquake machine she’d stood on once at the science museum – the ground kept shifting and changing, rising and falling under their feet, and it took all her concentration not to fall over. There was a great rushing, whooshing sound, of crashing waves and tearing wind.

And then it was suddenly quiet. They were standing on a narrow, dark street, in the middle of a muddy puddle. For a moment they clutched one another’s hands in breathless silence.

“OK,” Silver whispered. “We’re here.”