Her father wasn’t home yet when she returned to Hatmaker House, so Cordelia put the jar of strange green seeds on the kitchen table and dashed upstairs.

‘Supper in a few minutes!’ Cook called after her.

Cordelia found Great-aunt Petronella up in her Alchemy Parlour, peering skywards through a lunar spyglass.

‘There are waxing beams emanating this evening. An excellent fortifying ingredient and good for encouraging things. Come, Dilly, you’re strong enough to move my chair over to the Moon Mortar.’

Cordelia shunted her great-aunt’s chair across the parlour to the glowing Moon Mortar, which was smooth and shiny inside from years of having moondust crushed in it.

‘I want to do something to comfort Delilah Canemaker,’ Cordelia told her great-aunt. ‘I think she’s afraid of the Makers falling apart again, like they did when she was a child.’

The ancient lady nodded. ‘People are like trees,’ she said. ‘When you look at a tree’s rings, you can see that even the mightiest oak still has a sapling inside it. It is the same with people. And sometimes when a storm shakes a great oak, the sapling within quivers, remembering the storms it survived when it was very small.’

Cordelia considered this idea thoughtfully.

‘SUPPER TIME!’ came a shout from downstairs.

Sam and Len piled into the Alchemy Parlour. Together, Cordelia and the Lightfingers carried Great-aunt Petronella down to the supper table.

Prospero was back late from the docks, striding in through the kitchen door when almost all of Cook’s stargazy pie and mashed potatoes had been eaten and everyone was ready to move on to pudding.

‘Little Bear is afloat!’ Prospero announced.

Everyone round the table cheered this news as Cordelia leaped up to greet him. Even after months of having her father safely home, she still took every opportunity to give him the biggest bear hug she could manage.

‘I’m surprised you weren’t there to watch her go into the water,’ Prospero said, sitting down at the table and tucking into the slice of pie Cook had saved for him.

‘We meant to come!’ Cordelia cried. ‘But we got a bit distracted. You see –’

She looked around for the jar of seeds. They were not on the table where she had left them.

‘Caramel custard starlight pudding!’ Cook announced, placing a jiggling pudding in the middle of the table.

Cordelia jumped up to check the sideboard. ‘Cook, where’s –’

She broke off as she saw the empty jar by the pudding basin.

‘Where’s what, Dilly?’ asked Cook, dishing spoonfuls of caramel custard into bowls. ‘By the way, Sam, I thought that new starlight you brought home was a little strange!’

‘I forgot ta give it to ya, Cook. I’m sorry,’ Sam said, producing a glimmering handful of starlight from her pocket. ‘It’s here!’

She blew a bit of pocket fluff off it, and it gleamed innocently in her hand.

Cook frowned.

‘If that’s the starlight,’ she said, pointing her spoon at it, ‘then what was in the jar I used?’

Aunt Ariadne put her hand to her mouth. Cordelia felt her eyes widen as she realized exactly what had happened.

‘Nobody touch the pudding!’ Uncle Tiberius shrieked, leaping up to stand on his chair, as though there was a spider on the floor.

Cook dropped her spoon with a clatter and jumped back from the caramel custard as a small green seed wriggled up to the surface.

Uncle Tiberius gasped, eyes popping in alarm.

The seed shot through the air directly into his beard.

‘ARGH!’ Uncle Tiberius bellowed, batting himself in the face. ‘EVERYBODY, SAVE YOURSELVES!’ he wailed, losing his head and kicking the pudding on to the floor, where it smashed in a mess of broken china and oozing custard.

Cordelia saw several seeds pelt for cover under the table. She dived after them, smearing the custard into a slick on the flagstones.

‘Here’s one!’ she yelped, trying to catch a seed between finger and thumb. It wriggled away from her as her hands slipped in the mess.

‘How many were in the jar?’ Prospero asked Cordelia, joining her on hands and knees under the table.

‘About fifty!’

Prospero groaned.

They dodged out from under the table, just as Cook’s rolling pin arced through the air and smacked on to the floor between them.

‘This is so exciting!’ Great-aunt Petronella cackled, banging her spoon against her bowl.

‘We need to get Great-aunt P out of here!’ Aunt Ariadne gasped.

Cordelia leaped for another seed, but went skidding into Len’s legs and sent him crashing into the coal scuttle.

‘SORRY!’ she gasped.

‘Everybody, stay calm!’ Prospero barked, as though ordering the crew of a ship to remain level-headed during a hurricane.

‘THERE’S ANOTHER!’ Cook screamed, bringing her rolling pin down, missing the seed but smashing crockery as Sam gave chase, clambering over the table.

‘Got one!’ Prospero trapped a seed under a glass as it shot across the sideboard.

Cordelia skidded over to her father. The seed flung itself against the glass, whizzing in spirals. Prospero watched it with narrowed eyes.

‘Turbidus turbida,’ he muttered, tapping the glass.

For a moment, Cordelia thought her father was saying a spell. Then he went on: ‘This is a seed from the Turbidus Vine. One of the most troublesome plants in the world.’

Around them, the Hatmakers, Lightfingers and Cook continued to yelp and rush around frantically. The seed hurled itself against the glass.

‘QUIET!’ Prospero roared.

Everyone fell silent.

‘The plant responds to the sounds of chaos, so the louder you yell, the more troublesome it becomes,’ he whispered. He turned back to Cordelia. ‘These seeds are incredibly rare – where on earth did you get them?’

Cordelia explained in a quick whisper about what had happened in the park.

‘It must have been the Troublemakers,’ she concluded as softly as she could.

‘Well, they’ve finally let slip a clue about where they’re hiding,’ Prospero murmured. ‘You see, the Turbidus Vine only grows in one place: a mysterious island in the western Atlantic. It’s a place full of Menacing Magic – a place so dangerous no sensible person would go there.’

‘If there’s one thing we know about the Troublemakers,’ Cordelia said extremely quietly, ‘it’s that they really hate the concept of being sensible.’

‘The vines, roots and seeds all cause immense turbulence. Even a single seed, as you can see, has the energy to stir up an enormous heap of trouble.’

Cordelia looked around. Her father was right: the kitchen, usually kept so orderly by Cook, was in turmoil. Chairs had been toppled; there were shards of broken china covering the floor and splats of pudding sliding in sticky blobs down the walls. The seeds had caused this chaos within a matter of minutes.

Prospero carefully slid a spatula under the glass, flipped it over and tipped the seed quickly back into the jar, clamping the lid on tight.

‘I’ve got to go to Admiralty House right away,’ he said. ‘The Royal Navy have been waiting for a clue like this for months. They’ll finally be able to go after the Troublemakers.’

Cordelia felt her pride in her father swell like a rising tide.

‘Will you be able to tell the admirals exactly where to find them?’ she asked.

‘Not exactly where,’ Prospero admitted. ‘The island is uncharted; the Mapmakers made sure it didn’t appear on any seafaring maps. But this seed is a signpost that will point the navy in the right direction – we know the nearest island is a rather lawless place called St Freerest.’

Cordelia remembered how the secret society of Mapmakers had used enchanted maps to hide magical places, so they could not be found without a secret key or special directions. It was usually to protect magical places from being plundered by humans, but this time the Mapmakers had hidden the island to protect humans from being harmed by Menacing Magic.

‘This is a dangerous weapon,’ Prospero whispered, holding the seed up to the light. ‘Just a handful of these seeds flung at a person can cause them trouble for days – trouble sleeping, trouble concentrating, trouble balancing.’

Uncle Tiberius, either from the seed in his beard or from a dead faint, fell off his chair into the remains of the custard pudding.

‘How do we stop the missing seeds making more chaos?’ Aunt Ariadne asked, pulling Tiberius upright as Cordelia fetched the smelling salts. ‘They could be anywhere in the house!’

‘Keep as quiet as possible until we’ve caught them all. I just hope they don’t take root,’ Prospero said, pulling the kitchen door firmly closed as he swept his cloak around his shoulders. ‘Whatever you do, try and keep them out of the Hatmaking Workshop, or they’ll cause havoc with every hat we make!’

He strode from the house, tucking the jar safely into an inner pocket.

‘We’ve got a lot of cleaning up to do,’ Cook announced grimly, emerging from behind the vegetable rack, wearing a copper pot as a helmet.

Cordelia held the smelling salts under Uncle Tiberius’s nose and he jerked awake with a yell.

‘The Sensible Party will have a field day!’ he wailed.

‘Shhh!’ Cordelia hissed.

But it was too late. Excited by the noise, several seeds banded together and catapulted the vegetable rack.

Parsnips and cabbages went flying. A cabbage thunked Uncle Tiberius in the head, knocking him into a puddle of custard.