They found Lord Witloof in a quiet corner of the British Museum, locked behind layers of rippled glass and wrought-iron bars. It was what was left of Lord Witloof, anyway: a gnarled lump of lead, with a label beneath that read:

PLUMBUM WITLOOFICUS

The metal was twisted, like a scream that had been made solid. The last time Cordelia had seen it, it had been smoking in the core of an evil machine designed to turn human souls into gold. Lord Witloof himself had invented the machine and discovered, too late, that his invention would turn a wicked soul into a less precious metal.

Prospero Hatmaker had quickly realized that Witloof’s leaden soul was extremely dangerous: it could suck the magic out of a person with just the power of its wretched wail. He advised Parliament to lock it away in a dungeon deep beneath the Tower, but Sir Piers Oglethorne succeeded in persuading the other politicians that it was a valuable warning about the dangers of meddling with magic, and he insisted that it was housed in the British Museum for the public to see. Prospero, unwillingly, was forced to obey these instructions.

Before it could be safely put in the museum, Prospero and Great-aunt Petronella spent several days painstakingly constructing a cage of Pyre-Iron and Leechglass, to keep the terrible scream of the soul from sucking all the magic from the people who came to see it. Prospero had moved the soul into the museum at night, to make sure that if something went wrong, nobody would be hurt. Sir Piers himself had locked the cabinet that night, before taking the key to the prime minister, who kept it in a vault beneath Parliament.

Goose pressed his nose up to the glass beside Cordelia.

‘Father says it’s constantly screaming – the sound of Witloof’s last thought – and anyone who hears it will lose their magic,’ Cordelia croaked. ‘The Leechglass and Pyre-Iron muffle the scream, but Father wore Tight-Lip Limpets in his ears and Muzzle-Wool Ear Muffs while he moved it.’

Goose shuddered and backed away.

‘I wish they’d put it in a dungeon and thrown away the key,’ he muttered.

Sam peered in on Cordelia’s other side.

‘At least we know Witloof definitely ain’t the leader of the Troublemakers,’ she said. ‘C’mon – let’s get outta here. It’s creepy.’

They turned away from the glass case and set off through a gallery populated by ancient marble statues in various states of undress.

‘We’ve got to find a way to rescue Master Ambrosius!’ Cordelia burst out.

‘He should be freed once Making’s legal next week, shouldn’t he?’ Goose asked.

‘I dunno,’ Sam said dubiously. ‘They do love punishing people. Sir Piers would want ta make an example outta him.’

Sam and her brother, Len, having been pickpockets on the streets of London, had lots of first-hand experience of the severity of the legal system. Cordelia and Goose considered them experts in the field.

Halfway down the gallery, Sam stopped, staring up at a large stone block with small pictures carved on it.

‘Where’s all this stuff from?’ she asked. ‘I thought this was the British Museum. This don’t look British!’

Cordelia examined the statues.

‘It’s Egyptian, I think,’ she said.

‘Begged, borrowed or stolen, I wonder,’ Sam mused with a professional air.

Before Cordelia could answer, they heard loud voices echoing through the next gallery.

‘You’re meant to be quiet in the museum!’ Goose fretted.

The doors at the end of the gallery burst open and the king himself strode in.

Goose’s mouth went wibbly as he realized he had just admonished the most powerful person in the land for being too noisy. But His Majesty had not heard. He was being followed by his daughter, Princess Georgina, and the royals were mid-argument.

‘Is it too much to be obeyed in this one small matter?’ King George blustered.

‘Small matter?’ the princess wailed. ‘It’s not a small matter, Father!’

It did not sound like the kind of argument that wanted an audience. Sam dived behind the Egyptian monolith and Goose tucked himself between the stone folds of a Roman’s toga. Cordelia dodged round a statue of a grinning satyr embracing an unenthusiastic lady.

‘Being disagreed with is extremely disagreeable!’ the king complained.

A small, neat man hurried into the gallery behind the royals.

‘Ah! Your Majesty!’ the man panted, smoothing his wig as he bowed. ‘I’m glad to have caught up with you. I am Mr Smirke, the museum curator. Might I direct your noble gaze to the hierogly–’

‘We have the blasted Sensible Party on the royal back already, trying to get us to change our mind about the Makers!’ the king complained to Princess Georgina, ignoring Mr Smirke. ‘The last thing we need is our own daughter rejecting the perfectly good betrothal we’ve arranged for her.’

‘Why do you keep saying “us” and “we”?’ the princess asked. ‘Are you having another episode, Father?’

‘IT’S THE ROYAL “WE”!’ the king answered, exasperated.

‘Well, the royal me doesn’t want to be betrothed to Prince Hector!’ Princess Georgina insisted.

Cordelia watched through the stone limbs of the statue as the king rounded on the princess.

‘Why NOT?’ the king groaned. ‘He’s a PRINCE! Isn’t that every girl’s dream?’

‘I want to marry Sir Hugo!’ Princess Georgina argued. ‘I’ve asked you hundreds of times!’

‘Not this again!’ The king sighed, sinking on to a sarcophagus. ‘You can’t marry that actor: he’s a commoner!’ He grabbed a clay jar topped with an eagle’s head and waggled it at his daughter.

‘Ah, the ceremonial Jar of Horus, Your Majesty!’ Mr Smirke’s voice was edged with panic. ‘A most interesting artefact! Very valuable!’

‘You will be betrothed to Prince Hector of Bohemia, and I shall announce it in my speech to Parliament,’ the king growled, once more ignoring the curator. ‘It’s an important military alliance. Parliament will be pleased, even if you are not. That is the last thing to be said on the matter!’

There followed a silence bursting with unsaid things. The air strained. Mr Smirke managed to ease the ancient jar out of the king’s hand.

Cordelia heard the princess give one small, mournful squeak.

‘Don’t worry,’ the king said consolingly. ‘It’ll be several years till you’ll actually have to marry him. He should at least come up to your shoulder by then! Now, if you’ll excuse us, we are going to look at those incredibly silly long-necked cows in the next gallery.’

With that, the king trotted off through the crowd of statues, pausing only to admire a carving of a young man playing chess in the nude.

Cordelia kept out of the way until the king had gone, his royal guards striding behind him, with the curator scampering after them. She peered out from her hiding place to see the princess sobbing into her hands. She could not leave her alone and heartbroken, surrounded by a staring audience of cold statues. Sam and Goose pulled faces, shaking their heads when she beckoned them, so she alone sidled cautiously into view.

‘Your Highness?’ she ventured.

The princess turned, blinking her red-rimmed eyes in surprise. ‘Miss Hatmaker?’

Cordelia was about to bow and sweep off her hat gallantly, as she had seen her father do, but just in time she remembered that she had illegal nougat hidden under her hat, so she bobbed a curtsey instead.

‘Are you quite well, Your Highness?’ Cordelia asked. The answer was clearly no, but sometimes, Cordelia had observed, grown-ups asked each other questions with very obvious answers to pretend they hadn’t noticed anything unusual. Aunt Ariadne called this ‘being polite’.

‘Not quite well,’ the princess said, sniffing. ‘Actually, decidedly not well. In fact, I feel horrible.’

Cordelia was glad the conversation had steered away from politeness to a firm foundation of fact.

‘I don’t want to marry Prince Hector!’ the princess wailed.

Cordelia pulled out her handkerchief, which Great-aunt Petronella had hemmed with Cheering Cotton, and offered it to the princess, who took it and mopped her tears. But before Princess Georgina could begin to list her reasons for opposing the marriage, a long shadow appeared in the doorway. It belonged to a person who wore a crown and carried a sword that tapped the ground ominously.

‘This is BORING!’ the shadow lamented, stomping into the gallery.

Cordelia blinked as the owner of the shadow came into view. It was a boy, no taller than the princess’s belly button, carrying a toy wooden sword.

‘Prince Hector,’ the princess muttered. ‘My betrothed.’

Prince Hector made a face at Cordelia.

‘Why is that commoner here?’ the child demanded. ‘Make her dance or take her away!’

Bohemian guards, dressed in fancy frills, jogged into the gallery and seized Cordelia by the arms. She felt her feet leave the ground.

‘Put her down!’ Princess Georgina ordered. ‘That is my friend Miss Hatmaker!’

Prince Hector stuck his tongue out at Cordelia, who stared defiantly back, her feet still dangling.

‘We have much better Makers in Bohemia,’ Prince Hector announced, poking the guards with his sword until they dropped Cordelia.

‘Ah! Your Highness!’ Mr Smirke cried, scurrying back into the gallery. ‘I’ve been instructed to dazzle you with the finest treasures that the British Museum has to offer! See! Our fossils! Behold these old Egyptian sarcophagi! Observe the winged statue of Pegasus!’

‘Playtime!’ Prince Hector yelled, tumbling across the gallery to a statue of a winged horse.

‘I can’t marry him!’ the princess hissed as Cordelia dusted herself off. ‘He’s six years old! And besides –’

Her face melted into a sort of liquid look of longing.

‘Sir Hugo,’ she whispered. ‘I want to marry Sir Hugo.’

Cordelia remembered how the actor, who had long been interested in Princess Georgina’s royal personage, had finally caught her attention with a crumb of sunlight. Their romance had blossomed through the winter months. Sir Hugo had sent bouquets of Gladsome Roses to the princess, dedicated his performance as Romeo to her at the Theatre Royal, thrown himself in the path of Whistling Wasps at the Winter Ball to save her from their stings (and whistled his way through the role of Julius Caesar the entire following week). He had written his lady-love poems, sonnets and limericks, and even serenaded her from the shrubbery beneath her bedroom window, which had resulted in him being chased through the palace gardens by the pack of royal hounds. Cordelia suspected the princess had found this brush with death his most romantic gesture of all.

Now, a six-year-old prince with a wooden sword was the latest threat to their star-crossed romance.

Cordelia heard a yelp. Mr Smirke was wringing his hands in despair as Prince Hector swung from Pegasus’s wing.

‘Fly, horsey!’ Prince Hector urged, beating the statue with his sword.

‘Please desist, Your Highness!’ Mr Smirke wheedled desperately. ‘That’s a priceless antique! Perhaps we could all move into the new wing? I think we’ll find it most interesting!’

Cordelia saw Goose and Sam peering out from their hiding places as Mr Smirke ushered her, the prince and princess, and their guards through a door into a huge newly built gallery.

‘Here!’ Mr Smirke announced breezily, mopping his brow. ‘Isn’t it wonderful, Your Highnesses?’

The new wing had nothing in it except empty glass cabinets and vacant plinths. Cordelia looked quizzically at Mr Smirke, who planted himself firmly in front of the door that led back to the gallery of statues.

‘An unnamed benefactor will soon fill this new wing of the museum,’ Mr Smirke told her. ‘He’s collecting things from all around the world!’

Cordelia narrowed her eyes.

‘Collecting?’ she said.

Mr Smirke nodded.

‘Isn’t it really a sort of stealing?’

The curator puffed out his chest and said, ‘It is heroic! And patriotic! And nationalist–’

‘What’s he collecting?’ Cordelia interrupted.

‘Treasure!’

Cordelia nodded sagely. ‘It’s always treasure.’

Mr Smirke sniffed, bustling off to try to interest Prince Hector in an enormous empty plinth. ‘Our benefactor has promised us the head of a monster to go here,’ Cordelia heard him say.

‘WHY ISN’T THE MONSTER HEAD HERE NOW?’ the little prince wailed.

Princess Georgina slumped wretchedly against an empty cabinet. ‘I don’t know what to do!’ she groaned to Cordelia. ‘My father announces our betrothal in Parliament in two days’ time. Once it’s official I’ll never be able to get out of it – the Bohemians would take great offence. I have to change my father’s mind before then!’

The princess grasped Cordelia’s arm with a sudden fervent grip.

‘You can make a mind-changing hat!’ the princess whispered. ‘A hat that will change my father’s mind about the betrothal! And about Sir Hugo!’

‘Mind-changing hats are Meddling Magic; they’re not allowed …’ Cordelia began.

‘But they are possible?’

Cordelia nodded slowly.

‘Then you will start work on it today!’ the princess whispered.

Cordelia shook her head. ‘No, I really –’

But the princess had fire in her eyes. ‘It must be ready for my father to wear in Parliament on Tuesday! You’re my last hope!’

Cordelia found herself caught in the irrebuttable grip of royal entitlement. Clearly, royals did not hear the word no when uttered by a – what was that word she had heard several times today? – ‘commoner’.

Then she remembered she was face to face with a princess. It felt like a slightly inappropriate time to ask for Master Ambrosius to be freed, but it might be the only chance she would get.

She squirmed a little, as Aunt Ariadne’s frown and Master Ambrosius’s frightened face competed for attention in her head.

‘Could you persuade your father to pardon Master Ambrosius, Your Highness?’ she asked tentatively.

‘If you change my father’s mind for me, Miss Hatmaker, then of course I will!’ the princess promised, eyes shining.