By the time the Invincible reached the English Channel (a fact that Prospero whispered through the trapdoor early one mist-edged morning), the plan had become a patchwork of outlandish ideas sewn together with a great deal of daring and a hint of hare-brained brilliance.

Soon they turned into the Thames, and the smell of London fog and April rain startled Cordelia with its damp familiarity. When the Invincible docked and the admiral’s men came down to unload the cargo hold, they found everything as expected.

If some of the crates they hauled up on to the docks were heavier than they had been when they were loaded on to the ship, nobody noticed.

And nobody noticed the occasional eye peeping out from between the planks of the crates as they were piled on to carts and rumbled through the streets of London, up from the docks at Wapping and along Cheapside towards the British Museum …

‘I feel a lot more seasick on land,’ Goose grumbled. His face was squashed against the side of the crate. Sam, whose legs were folded at an uncomfortable angle, agreed queasily as the cart joggled over cobbles.

Cordelia looked at them both sideways. She had to look at them sideways because her whole self was sideways, wedged between the severed trunk of a palm tree and some slippery seaweed that had developed a terrible smell.

‘It shouldn’t be much further,’ she told them. ‘Listen! That’s the clock at High Holborn!’

A number of dolorous clangs gloomily announced it was nine o’clock.

Cordelia twisted round to put her eye to a small knothole in the crate. Every Londoner was dressed in grey, with faces to match. They passed the Mercurial Chocolate House on Red Lion Street and saw it was boarded up.

The Sensible Party had got rid of everything fun.

Goose managed not to be sick as their crate was lifted off the cart and carried a jolting, twisty distance by two grunting men before finally being dumped on to a cold marble floor.

For a long time, they stayed very quiet, listening to the sounds of crates being shuffled in and set down all around them. Then they heard the whine and rumble of voices approaching.

‘All delivered here to the new Ransom Wing!’ came the cannon-boom voice of Admiral Ransom.

Then Cordelia recognized the drawl of Sir Piers Oglethorne himself.

‘This must be kept secret, do I make myself clear, Smirke?’ he said. ‘Nobody else is to be allowed in until seven o’clock tomorrow night.’

‘Yes indeed, sir!’ came the reply, in a voice so oily you could slip on it. It was the museum curator, Mr Smirke.

‘The grand opening of the Ransom Wing!’ Admiral Ransom blared. ‘A victorious return, with the head of a slayed beast, and the rescued girl alive and well.’

The voices arrived right beside the crate.

‘In truth, your daughter was a nuisance all voyage long, Sir Piers: cursing me through the keyhole and singing loud songs when I was trying to sleep.’

They were so close it was possible to hear the hiss of Sir Piers’s displeasure. Cordelia couldn’t help grinning at this – Thorn had clearly not lost any of her spikes.

‘Prudence must be subdued somehow until tomorrow evening,’ Sir Piers said. ‘I don’t want her looking unhappy to be back; people would ask too many questions. I’ll put her in the front row of the audience – along with all the Makers, who will be brought here by soldiers, to make sure nobody misses the special surprise I’ll have waiting for them.’

‘There’s a lot of work to be done, Smirke!’ the admiral bellowed. ‘I’ve brought thousands of objects back and I want them all on display by tomorrow night.’

‘You get the glory, Ransom, and I get the power,’ Sir Piers said drily. ‘Just as we agreed months ago.’

Smirke’s simpers faded as he escorted them out, then their voices were snipped off like cut string as the door closed.

Cordelia listened for a long minute, then pushed the lid off the crate and poked her head up.

‘Double, double!’

All over the Ransom Wing, heads popped up from crates as Troublemakers appeared one by one. Soon they were stretching their stiff limbs and staring around the huge gallery, with its high white walls and empty cabinets and plinths.

In the middle of the room, clenched like a grey fist and sealed inside a cage of glass and iron, was Witloof’s soul. Its silent scream pulled them like an undertow, dragging their eyes into its dark gyre.

It would only become dangerous when Sir Piers opened its glass box, which had been expertly made to muffle its dreadful scream. But even now Cordelia shuddered at the dark pull it exerted. She didn’t want the others to become frightened, so she quickly covered it with an empty sack.

There were a hundred crates and dozens of sacks waiting to be unpacked. The admiral had clearly gone about robbing with spectacular abandon.

Sam opened one chest to find that it contained dozens of crystal stalactites that had been sawn from the ceiling of the Belly Cave. They were dull and sad, having lost their glow when they’d been ripped from their rightful place. Goose upturned a sack, emptying shrivelled fungus puffballs on to the floor. Tabitha found a crate of glowing cocoons, and lantern flowers that had been ripped up by the roots.

The trunk of the Soulhope Tree lay across the floor like a slain giant.

As Cordelia touched the stolen treasures, a shocking sadness ran from the tips of her fingers right to her heart. These treasures had been carelessly torn from their homes and brought here, the spoils of ransack, reeking of ruin.

Then she noticed that one of the boxes was humming. Another clucked. A third jiggled and snuffled.

‘Some are still alive!’ she murmured.

There was a label pasted over one with the words FOR TAXIDERMY stamped across it.

Never joined her. As he read the label, his face became angrier than Cordelia had ever seen it.

‘Typical of the Sensible Party – if anything’s magical, lock it up and throw away the key,’ he burst out. ‘And if you can, kill it and stuff it! Make sure the light leaves its eyes!’

A wet nose snuffled between the planks of one of the boxes; a mournful honk came from another.

Cordelia opened the lid and an inquisitive face peered up at her.

‘You survived!’ she gasped. ‘I’m so sorry you were captured!’

She lifted the dodo out of the crate. The bird was heavy in her arms, but it nudged her cheek in a friendly way.

‘You must have been so lonely,’ she said to it.

She looked across the pile of crates, humming and buzzing, clucking and snuffling. Dozens of creatures were trapped in boxes. According to the labels, they were destined to be –

‘No visitors allowed in here!’ an imperious voice rang across the room.

Cordelia swung round. Mr Smirke had returned – and he seemed likely to burst with indignance when he saw what Cordelia was holding.

‘That beast is going to be killed and stuffed for the display!’ he snapped. ‘Put it back at once! You might damage it!’

‘Damage it?’ Goose spluttered. ‘You’re the one who’s planning on killing the poor creature!’

The curator snapped his fingers, striding forward. But he had only taken a few paces when Cordelia squared up to him.

‘There’s only one beast in this room that’s going to be stuffed and put on display,’ she growled.

She felt thorny and furious.

Mr Smirke reared back and scurried for the door. But the Troublemakers had blocked the way out. When he opened his mouth to yell for help, Shelly promptly stuffed a gob of seaweed into it.

A few minutes later, Mr Smirke became the first object to go into one of the Ransom Wing display cabinets, with dodo feathers stuck in his hair and several large orange snails moving slowly across his forehead. He stared at himself with treacle-slowness.

‘He’s not very interesting as a display,’ Sam observed. ‘But at least he’s outta the way.’

The dodo honked mournfully.

‘He’s not going to stuff you – don’t worry, sir,’ Cordelia assured the bird.

But she turned seriously to all the Troublemakers.

‘Tomorrow night, Sir Piers is going to open the soul-lead cabinet and bleed the magic from everyone at the grand opening: every Maker in the country, and Thorn – and us too, if we’re in this room to hear the scream.’

She had to be sure the Troublemakers knew exactly how dangerous things would get.

‘Anyone who wants to can leave and hide until it’s over,’ Cordelia assured them. ‘I’m going to stay and try to stop him.’

‘I’m staying,’ Goose added.

‘Me too,’ Sam said.

A chorus of determined nods and fierce growls told Cordelia that every Troublemaker would stay.

‘What’s the plan?’ Never asked.

Cordelia surveyed the brave faces surrounding her.

‘We Make Trouble.’