Lily and Robert swerved up the drive of Brackenbridge Manor, with Malkin scampering along behind them. They aimed their bicycles through the open doors of the stable block and came clattering to a stop.

Malkin sniffed at a pair of metal feet sticking from beneath the front of a steam-wagon.

“Leave it out!” Captain Springer rolled himself out from beneath the vehicle’s chassis. His metal face was covered in engine oil, but that wasn’t unusual given that he was a mechanical. He dropped his spanner into his big tin toolbox and rooted around for something else. “Your father’s looking for you,” he told Lily. “You’re late for breakfast again.” He gave a tut like a ticking clock. “An engine can’t run without fuel, you know, tiddlers.”

“We know,” Lily told him. She and Robert left their bikes against the wall in an empty stall and hurried through the yard into the house.

They arrived in the dining room to find Papa already seated and tucking into a plate of kippers.

“Ah, the wanderers return!” he cried. “Zep-spotting, I take it?”

Malkin jumped up onto a chair and deposited The Daily Cog on the table. “Merely collecting the paper. Here you go – it’s hardly mauled.” He nudged the paper towards John with his nose, then jumped down and slunk under the table.

Papa smoothed out the crinkled pages. Lily half-expected him to start in straight away on the sensational story about the jailbreak, but instead he opened the technology section and, taking up his half-moon glasses, peered through them at the tiny printed articles.

“Aren’t you going to read the headlines?” she asked, as she reached over and snatched the puzzle pages for herself.

“This item’s far more interesting,” Papa muttered.

Lily gave a big sigh; she was too hungry to argue. Besides, she knew he wasn’t listening. He’d be lost in reports of the new inventions being built around Britain.

Mr Wingnut, the mechanical butler, bustled in. His metal brow furrowed in concentration as he set down a silver tray and gave a bowl of porridge and a plate of bacon, eggs and toast to each of them.

There was too much food again. Mrs Rust, the cook, had never quite got the hang of quantities and consequently would overdo things a little in the kitchen. But two breakfasts suited Lily down to the ground; she sat at her place and tucked in immediately. After so much cycling she felt as if a hungry army was marching round the pit of her stomach demanding feeding.

She scoffed down alternate mouthfuls of porridge, toast, bacon and eggs, and glanced at Robert across the table. He gave her the wannest of smiles. His complexion had turned terribly pale and he was barely eating. Lily hadn’t noticed before, but tired grey circles had grown under his eyes.

She was sure it was visiting the shop that did it. For a while a suspicion had been growing in her that Robert had been making secret excursions there regularly. He tended to disappear at odd times, when he imagined no one would notice. But Lily did. She always noticed where he was – it was as if she was extra-sensitive to it. Catching him at Townsend’s today had only confirmed her suspicions: he was aching for his old life. She knew what that was like, but dwelling on the past could only make you upset. Her heart went out to him.

Lily missed Mama every day. It could be a pain in her chest, as if a cord that once tied them had been broken, or the tiniest itch of a memory. Half-forgotten hugs and faded conversations – they rattled around inside her and came out sometimes, like catching the slightest whiff of a faded scent that you can’t quite place.

The pain of loss must’ve been keener for Robert, since the cut was fresh and deep. He probably thought of his da every hour of the day. And perhaps he felt he couldn’t say, or worried she, or Papa, would see that as ungrateful. But Robert was silly to imagine he couldn’t be truthful with them.

“Listen to this.” Papa shook out the newspaper. “Parliament today voted to build a new power station on Lots Road, in the London borough of Kensington and Chelsea, with plans to move ahead with electric power for the whole Underground and West London.”

“That’s not interesting,” Lily said.

Papa straightened his glasses, which had gone wonky on his nose. “Of course it’s interesting, Lily. Electricity is the future. Why, ever since Edison first lit up the street lamps on the Holborn Viaduct fifteen years ago, engineers in London have been striving for bigger and better power stations that will transport electricity efficiently around the city and, one day, around the country.”

He began moving condiments about on the table. “I mean, imagine this pepper pot is the power station, and this fork a railway train, or better yet, this knife.”

“That’s my knife!” Lily cried. “Give it back! I’m eating!”

Papa waved it at her. “But listen, Lily…this is important. Within your lifetime, there may be no more clockwork engines, or steam-wagons. The fact is, soon, everything will run on electricity.”

Lily snatched her knife from him and cut another slice of bacon.

“After that,” Papa continued, “mechanists like me will be out of a job. Mechanicals too. A multitude of electrical appliances will take their place.”

There was a crash in the background as Mr Wingnut dropped his silver tray, spilling a plate of kippers on the floor.

“Sorry!” he mumbled, and Lily heard him muttering, “What clacking nonsense,” under his breath as he bustled about picking up the tiny fish bones that were stuck to the carpet.

“In the meantime,” Lily said, tapping the front of the newspaper frustratedly with her eggy fork, “you’re ignoring the most exciting story of the year, right under your nose. The daring jailbreak of a vicious convict named Jack Door, written by our friend Anna.”

Papa stared at the headline splashed beneath the masthead. “Well, well, I see she’s their lead reporter now. A female lead, whatever next!”

Lily tutted. “Plenty of ladies are lead reporters, Papa. Haven’t you heard of Nellie Bly, or Elizabeth Bisland?”

“Why bless my soul, of course I have!” Papa peered at the article. “Who’s this blackguard Jack? He robbed the Queen, it says…”

“Yes,” Lily replied. “He was given a life sentence. And then he wrote a book in prison called The Notorious Jack Door: Escapologist and Thief Extraordinaire! It was serialized in the penny dreadfuls, but I read it as a book last year. It’s marvellous!”

“Sounds more scandalous than marvellous,” Malkin said.

“And a mite scary, if Anna’s article is anything to go by,” Robert added. “How’d he sneak a novel out of jail, anyhow, if he was being held in maximum security?”

Lily took a big bite of toast. “Nobody knows. But he managed it somehow – if you’re an escapologist you have those kind of skills, Robert.”

Robert pushed his food aside; he hadn’t eaten much, he was too busy thinking about the ghost at the window. At least Lily’s story was a distraction. “That’s what Jack’s book’s about then?” he asked. “His famous tricks and robberies?”

“Not really,” Lily said, spraying toast crumbs across her plate. “It mostly tells you how to pick locks. That and how to break unbreakable chains…oh, and how to tie untie-able knots.”

“Why on earth would you need to know any of that?” Papa asked.

Lily licked the end of her finger and picked up the crumbs one by one. “It came in handy when we rescued you, didn’t it?”

“If I recall correctly,” came a voice from beneath the table, “I was the one who did the better part of the rescuing on that occasion.”

Lily ignored Malkin and examined page two of the paper. “There’s a little more about Jack’s history here… It says he once had a show in the West End with his family. His wife was a spiritualist, and he was some sort of a magician and expert in escapology. When he bored of that, he started using his skills to steal from country estates – that was before he pinched the Queen’s diamond.”

“How’d they know he did those other robberies?” Robert asked. “It could’ve been anyone.”

“Ah.” Lily smiled. “He had a calling card. At every house he burgled, he left a Jack of Diamonds pinned to the wall. That’s how they got him in the end. Well, that and someone gave up his location to the police.”

“What a tockingly stupid way to incriminate oneself!” Malkin exclaimed.

“Quite,” she agreed. “He even tied a playing card to the Elephanta’s tail, when he stole the Blood Moon Diamond live onstage. So there was no need for the police to use their new fingerprinting techniques to prove his guilt. They locked him up for life on the strength of those cards.” She peered down at the article. “Anna’s called his jailbreak the most audacious ever.”

“Zeppelins and zoetropes!” said Mrs Rust, who’d come in with a plate of muffins during Lily’s chatter. “Let’s hope he never comes round here. That rogue’s probably gone right back into the burgling business.” She stooped on her way back to the kitchen to help Mr Wingnut clear up the dropped kippers.

“He’s not interested in inventions, Rusty. He only stole jewellery, and we don’t have any of that.”

“Houndstooth and herring bones! I should think not,” Mrs Rust spluttered.

“And thank tock for that!” Mr Wingnut added.

“There’s more,” Papa said. He was fascinated now, and perusing the article himself. “It says the diamond was never recovered, despite a ten-thousand-pound reward, and during his fifteen long years in prison the Jack of Diamonds never revealed its whereabouts.”

“That’s his nickname,” Lily whispered to Robert. “Because of the playing cards.”

Papa gave a loud cough, for he hadn’t finished reading. “On top of the original reward for the recovery of the Blood Moon Diamond, a further reward of five thousand pounds has been offered for any information that would lead to the rearrest of Jack.” He pushed the paper away and took a contemplative bite of his toast. “We could do with a little of that money ourselves!”

Lily realized he was probably right. Despite Papa trying to hide it, things had been a little sparse of late. Perhaps it was because Madame Verdigris and Mr Sunder had run off with a lot of Papa’s valuable patent papers last year, and they still hadn’t got them back.

That last thought seemed to jolt Papa from his chair, and he stood, folding the paper under his arm.

“Enough of this,” he said. “I’ve work to do. I have to finish repairing Miss Tock.”

Normally after breakfast Lily and Robert had lessons in the nursery, supervised by Mrs Rust, but halfway through a particularly boring reading comprehension they’d been doing, the mechanical had wound down, and they’d taken the opportunity to sneak off and see what Papa was up to.

The lightning bolt on the workshop door was supposed to symbolize danger, but Lily liked to imagine it represented the inspiring things that filled Papa’s workshop. She turned the door handle and she and Robert stepped inside.

It was an amazing space, bigger than Robert’s da’s old workshop and filled with more clockwork than the insides of Big Ben, but a certain cosy quality was absent. Robert found the rest of Brackenbridge Manor like that as well – a little too grand, a little too imposing. It never quite felt like home, because everyone was spread so far apart.

“Done with your schooling already, are you?” Papa glanced up, and Malkin, who lay underneath his chair, nipped at his shoelaces. He brushed the fox away and stood, beckoning them over. “Come and look at this, a proper clockwork brain!” he said, indicating Miss Tock, the mechanical maid, who sat wound down on the workbench, her stilled legs dangling beneath her, a panel in the front of her skull open. She had banged her head while dusting and doing the housework, knocking a cog loose, and it had been rattling around and making her act strangely ever since.

Papa fished out the troublesome cog and waved it at them. “These cogs connect up, much like the synaptic links in your heads. Their turning allows ideas to pass through her consciousness. One piece out of place and she’d never remember what day it was!”

Papa’s talk of clockwork made Lily’s mind drift to her own clockwork innards and worries. Her sense of not fitting in, of being a square peg in a round hole. It wasn’t just the Cogheart, pumping blood around her body with each mechanical heartbeat, that made her feel that way. Even before she knew she had a perpetual motion machine for a heart, she’d always felt different to other girls. The truth was, discovering she might live for ever had only made her feel more out of sync with the world. She glanced at Robert, but he didn’t seem to be concentrating either.

The trouble was he couldn’t shake the image of his da’s face at the window. Could it really have been a ghost? For a second Robert wondered if he should ask Professor Hartman, but then he decided against it. He didn’t want to worry him unduly. The professor would probably say he’d been imagining things, or was going mad. He tried, instead, to focus on what John was saying, but all this talk of clockwork made him think of his old life as Da’s apprentice and that made him miss Thaddeus even more.

“There.” John replaced the final gears. “That’s the last of these complications. She’ll be ticking royally once again in no time.”

“Oh my goodness! I forgot!” Lily pulled her purse from her pinafore with such force that the letter, her ammonite, watch and money flew from her pocket and scattered across the table. She scooped up her things and handed Papa the letter. “We received this in the post – Mr Brassnose at the airstation said it was from the Queen.”

“You forgot a letter from the Queen?” John looked incredulous.

“I…” Lily looked embarrassed. “I was so intrigued by the jailbreak story that it clean escaped my memory.”

“Never mind.” John put the letter on the workbench beside Miss Tock and carefully finished screwing the panel on her head up tight.

“Well,” cried Lily, “aren’t you going to open it?”

“I can, if you like…” Robert reached for the letter.

“In a moment.” John propped his elbows on the workbench and steepled his hands, as he always did when he was trying to give a lesson. “Patience, you know, is a virtue. First, we have to finish with Miss Tock here.”

“This is hardly the time for lectures, Papa.” Lily stepped towards him, so that she might lunge forward and see the letter.

“Yes,” said Robert. “Please, let’s hear what it says.”

John sighed and picked up the envelope, breaking the seal and slitting it open with his screwdriver.

Lily and Robert leaned in close. Even Malkin – who was the sort to pretend he received letters from the Queen every day – jumped up onto the workbench, so he might see what was going on.

John put down the screwdriver and, with a grand flourish for his audience, reached into the envelope and pulled out a thick wodge of cream paper.

He unfolded it carefully but, as he began to read, his smile faded. “Good heavens!” he muttered.

“What is it?” Robert asked. “What’s the matter?

“Yes,” Lily said. “Tell us.”

John cleared his throat. “The Queen wants me to travel to London, to the Mechanists’ Guild, and repair the Elephanta.”

“You mean the mechanimal Jack stole the diamond from?” Robert asked.

“That’s right.” John nodded. “She was the first mechanical creature ever created. Prince Albert had her made for the Coronation. The missing Blood Moon Diamond is what powered her. The Queen seems to think I, as a renowned mechanist and maker of mechanimals, might find a way to bring her back to life so she can take part in the Jubilee.”

Robert was aghast. “But that’s only four days away! An impossible task!”

“Not for Papa,” Lily said. “If anyone can fix the Elephanta, he can.”

“I don’t know, Lily…” Papa replied.

“Of course you can. You’re the greatest inventor in the land. And if the Queen’s requested you, she must think so too.” Lily wondered if she was brave enough to make her next suggestion. “But with so little time you’ll need us to come to London and help with the work.”

Papa shook his head. “No, Lily, you and Robert will stay at home. I don’t want you getting into any new trouble. I’ll be in London under my own name and I don’t want to draw attention to us. Besides, you’ve everything you could wish for here, haven’t you?”

“But, Papa…”

“No buts; my mind is made up. And, as for being the greatest inventor in the land… I want people to forget me. Forget us. It’s the only way we can ever hope to remain hidden. There are greedy opportunists about, Lily, and if they discovered how unique you are, then you’d have a price on your head – or, to be more exact, on your heart. I can’t risk losing you like that. I’ve already seen you at death’s door twice, and lost your poor mama. You’re the only thing I have left, all I’m holding on to.”

He turned away and gave a sniff. Then folded the letter, and replaced it in the envelope. “So I think it best you stay at home.”

“Can we at least go to the village school while you’re away?” Robert asked. “We’d come to no harm there, surely?”

“Mrs Rust and the mechanicals can continue to teach you,” Papa countered. “Meantime, I shall go undertake the Queen’s work. Were it not for the money, I would not risk drawing attention to myself, but I shall complete the task and return as quickly and quietly as possible. Then we can catch up with extra lessons.”

Lily listened to his speech with a heavy feeling of doubt. Papa was living in the past, trying to keep them hidden. Those dangers were gone now, she was sure of it. And in any case, couldn’t he see she was almost grown, and perfectly capable of taking care of herself? Why, she even helped him with his work. But Papa didn’t think in those terms. In his world she would stay squirrelled away for ever, like some sort of secret.

“I think we’re done.” Papa wound Miss Tock up with her winding key, and they waited…as slowly, very slowly, she jittered to life.

“By all that ticks!” she exclaimed. “It feels as if I slept for a thousand years. What did I miss?”

“Nothing much.” Malkin yawned. “Just a letter from the Queen.”

“Is that all!” Miss Tock clucked. “Well, thank clank for that!”

Lily wondered if she had understood Malkin entirely, but Papa seemed sure she was fine.

“You should run as good as new now,” he told Miss Tock. “Lily will show you out, won’t you, Lily?”

“Of course.”

After Lily had assisted Miss Tock to the door, she and Robert helped Papa pack away his tools. Suddenly, Papa stopped and stared at them.

“Robert, I wonder if you might accompany me to my study after this? There’s something I wish to discuss with you…about your, er, situation.”

Robert’s stomach gave a sudden lurch. He knew exactly what the professor meant – a mercurial mixture of ghosts, burned shops, and visions of his missing ma sloshed about inside him, threatening to overflow. Ever since Da’s death six months ago, the professor had been trying to help Robert trace his ma; so she could be alerted to his predicament and they could sort out this mess with Townsend’s Horologist’s. Could he have made a discovery? If he would only reveal it in private, Robert was pretty sure it must be bad news.