There were three things everyone knew about Lily.

 

Firstly, she had two brothers and half a sister. All of them were older than Lily. There was Willy the Wizard, Billy the Beast-Tamer and Milly the Magician. Willy ran his own potion shop in the Magic Market. He knew all there was to know about potions. Wizards and witches would come from all around the world to buy from his shop, or ask his advice on mixing troublesome remedies. Billy worked at the magic zoo, teaching the little dragon hatchlings how to fly and, eventually, how to breathe fire. Milly had been Magician to the Queen, until it had all gone wrong at one performance, and she had been shrunk to the size of a glue stick. Now, only ten centimetres tall, her voice was too small and quiet for the magic winds to hear.

 

The second thing everybody knew about Lily was that she was only responsible in part for the fact her sister had shrunk to such a size. It had been an unfortunate mix-up. Milly had asked Lily to read the spell of invisible ink, but one of the corgis had barked at that moment, and Lily read instead the spell of infinite shrink. Milly had shouted at Lily and told her how to undo the spell but, since Milly was so small, Lily couldn’t hear her at all. Milly blamed Lily, and Lily blamed the corgi.

 

The final thing, which everyone knew and accepted, was that Lily was the worse magic-user in the world. Tilly the Terror, who had turned her own mother into a talking unicorn by mistake, had enjoyed more successes than Lily. Even Jilly the Jinx, who had experimented with her wand backwards and caused all the snow to go upwards, had eventually mastered the art of magic. But Lily just couldn’t. No matter how often she practised, her spell-making never improved. Eventually, on her eighth birthday, Lily snapped her wand in half and decided to become a librarian. After school, she would go to the library and help Dilly Dotty, checking-out books and returning the ancient magic scrolls to their correct spaces on the shelves.

 

One thing very few people knew about Lily, including herself, was that her parents were secret agents, who rescued magical artefacts for the government. Each morning Mr McIll would leave the house in a suit, and Mrs McIll would take Lily to Alchemy Academy before rushing off to join her husband. They had uncovered some of the most famous magical objects in the world, including The Hilarity Horn, which caused anyone who heard it to fall into fits of laughter, and The Writhing Ring which made the wearer itch all over. But their crowning glory was The Iris Eye. The Iris Eye was a small glass sphere which looked like a marble, but if you looked at someone through it, you could see what they were thinking. They had only just rescued it from Lord Quill, sneaking into his castle to recover this magical object which he had stolen from the vaults of the Spectral Station.

 

It was a normal Thursday and Lily was waiting in the playground at the end of the day. The library was closed on a Thursday because Dilly Dotty went to visit her uncle, so Mrs McIll would meet Lily at the school gate. This had happened every Thursday for months, but today there was no sign of Mrs McIll. Lily stood by the gate and waited as, one by one, her friends went home. Mrs McIll had never been late before. If she knew she wasn’t going to get there on time, she would ask Lily’s friend’s mum to pick her up.

 

Lily walked back into the classroom and explained to her teacher, Mr Hill, what had happened. Mr Hill let Lily sit in the classroom while he rang Willy’s shop and asked him to come and pick Lily up from school.

 

“I can’t come yet,” Willy explained. “I’ve got a queue of customers. I’ll send Billy over.”

 

Billy arrived on a unicorn he was training, and he and Lily went home together.

 

Later that evening Willy, Billy, Milly and Lily sat around the table eating dinner. It was fish fingers for everyone, except for Milly who just had a pea. None of them spoke, but Billy kept sighing and looking across at the empty chairs where their parents usually sat.

 

“I think we should call the police,” Willy said at the end of dinner. “There’s nothing in the diary, so they didn’t have anything planned.”

 

“Do you think they’ve been kidnapped?” Milly asked, but no one heard her tiny voice.

 

Billy walked over to the telephone which was beside the front door, but as he lifted up the receiver there was a loud knock at the door. All four of the McIll children jumped. Billy opened it and found two men standing there. One was wearing a tidy suit and had a stern face, but the other was wearing a woolly jumper with a picture knitted on it. It was a picture of a phoenix with a snake in its claws. All the children knew at once what it meant. It was the sign of The Guild of the Guardians, a branch of the government who protected magic.

 

“Willy, Billy, Milly and Lily McIll,” the man in the suit began. “Do you know who we are?”

 

Willy and Milly nodded, and Billy and Lily shook their heads. Billy invited them in, and Willy made them a cup of tea.

 

“We don’t have long to explain,” the man in the jumper continued. “We were expecting your parents back at the Spectral Station hours ago, but they never returned.”

 

“The Spectral Station?” Lily asked. “Why would they go there?”

 

“Because they work there,” the man with the suit said. “Your parents are both secret agents in The Guild of the Guardians. We’re worried they’ve been kidnapped by Lord Quill.”

 

“Why would anyone kidnap Mum and Dad?” Willy asked.

 

“Because they have the code to the vaults of the Spectral Station.”

 

“Wow,” Billy breathed, full of surprise at this new discovery. “I thought they just had boring jobs.”

 

“We have to get them back,” Lily said. Everyone in the room looked at her, nodding in agreement.

 

“There is a problem,” the man in the jumper said. “Lord Quill lives in the middle of The Feral Forest, in a castle with fifty guards, and he knows everyone who works for us. We’ll never get in.”

 

“He doesn’t know us,” Willy said boldly.

 

“And I know how to get us to the castle without having to go through The Feral Forest,” Billy added.

 

Milly nodded as she picked up her tiny wand.

 

“I’ll go, too,” Lily announced.

 

Everyone froze. They couldn’t risk Lily’s disastrous magic when they had to rescue their parents. Milly shook her head and tapped Lily’s hand.

 

“You’ve got homework,” Willy pointed out.

 

“And it’s almost your bedtime,” Billy agreed.

 

“Someone must stay and protect the house,” the man in the jumper said.

 

“No,” the other man said. “Lily should go, too. You’ll need all the people you can take, and four is a good number.”

 

Lily smiled, feeling suddenly excited, but when Billy stood at the door and whistled a series of low notes, she began to change her mind. A huge Roc landed in the garden. The bird’s wing feathers were as tall as Lily. Its beak could have swallowed her whole. Billy put Milly on his shoulder and climbed up onto the Roc’s back. He helped Willy up and they nestled into the bird’s feathers so they wouldn’t fall. Lily was too scared to climb onto its back, but as it flapped its enormous wings, it snatched her in its talons and carried all four children easily into the air.

 

At first, Lily had cried and screwed her eyes closed. As they flew over The Feral Forest though, she looked down and gasped at how beautiful it all looked. There was still snow on the trees and it looked like a Christmas card as they shimmered in the moonlight. She could almost imagine tiny baubles and snakes of tinsel on each one of them.

 

There was no need to ask when they would arrive. Lord Quill’s castle, with twenty towers, was already clear on the horizon. It was made of dark grey stone and had only tiny windows letting out even fewer blobs of light. Through a series of quiet whistles, Billy told the Roc to put them on the top of one of the towers.

 

The Roc set them down. All four of them watched as it flapped its wings and flew away, fading into the night sky. They all felt nervous as they looked about the flat top of the tower, trying to find a way into the immense castle. Milly pointed down, pulling Billy’s hair to get his attention. She had found a trapdoor. Billy was about to lift the handle when Willy spoke.

 

“I brought this,” he said, pulling a little bottle out of his coat pocket.

 

“What is it?” Lily asked.

 

“It’s a potion of invisibility. But if we all drink it out of the same bottle, we’ll be able to see each other.”

 

“That’s amazing,” Lily whispered, wishing she was clever enough to know about beasts and potions like her brothers.

 

Each of them took a gulp from the bottle. They couldn’t tell any difference, but one by one they faded into the night, becoming as transparent as the wind. Billy heaved open the huge trapdoor and found a flight of stone steps spiralling away from them. As quiet as mice they tiptoed down the stairs. They didn’t stop until they walked through a doorway and found themselves on a large landing. There was a beautiful wooden staircase which wound down to the ground, but their eyes were all fixed on two guards in suits of armour who were sitting at a small table next to a heavy door, playing noughts and crosses.

 

All four children held their breath, not really expecting the potion to work. But the guards didn’t see them, even when Billy knelt beside them and pulled funny faces. Willy took a pencil out of his pocket and wrote on a scrap of paper:

 

“They’re in here.”

 

He pointed at the door next to the guards.

 

Willy was the tallest of them and could see through a barred window near the top of the door. They all stared at the door, trying to work out a way into the room. As Willy, Billy and Lily pondered this, Milly leapt off Billy’s shoulder and onto the table. She picked up a piece of pencil-sharpening which was just the right size as a megaphone for her. Lifting her wand, she cast the spell of silent sleep over the two guards. Her brothers and sister all congratulated her on her idea, and they looked for the keys on the sleeping guards. But the keys weren’t there.

 

“Lord Quill must keep them,” Milly said through her pencil-sharpening megaphone. Her voice was like the tiniest whisper, but Lily felt relieved Milly could make herself heard again.

 

“Is that you, Willy?” they heard their father’s voice say, and all four children rushed to the door.

 

“Can we go home, now?” Lily sniffled. “How can we get Mummy and Daddy out?”

 

“Lord Quill keeps the keys,” Mrs McIll said through the bars. “It’s too dangerous to try and get them.”

 

“But what if we don’t need a key?” Milly asked. “I’m just the right size to sneak into the keyhole. I could open it without the key.”

 

“That’s a brilliant idea,” Billy agreed, lifting Milly up to the keyhole.

 

“Be careful,” Mr and Mrs McIll said at exactly the same time.

 

“And hurry,” Willy added. “The potion will be wearing off soon.”

 

Milly nodded and crawled into the keyhole. It was a tight squeeze, but she managed to sit on a small ledge, using her feet to kick open the tiny mechanisms of the lock. Feeling very pleased with herself, she climbed out onto Mrs McIll’s hands and smiled proudly as Mr McIll opened the door. The invisibility potion was fading now, and Willy, Billy and Lily were all emerging like shadowy forms as they ran forward to hug their mum and dad.

 

“Come on,” Billy said quickly. “We can escape the same way we arrived.”

 

All of them turned at an evil laugh. Lord Quill stood there with fifteen guards, all wearing armour, and carrying magic swords which shone a vivid green. But it was Lord Quill himself Lily stared at. He was hardly human, with glowing white eyes and skin so pale it looked like the sun on water.

 

“You will not escape,” he said, his forked tongue hissing the words.

 

“He’s a wraith,” Billy gasped.

 

“Yes,” Mr McIll nodded. “None of our magic is powerful enough to beat him. There is no potion to conquer him, and no beast who can stop him.”

 

Lily stared, her eyes widening as the ghostly snake-like man walked forward. Willy couldn’t help. Nor could Billy. Even Milly’s strong magic spells could not compete against a wraith. Their parents positioned themselves between Lord Quill and their children.

 

“What can we do?” Lily asked, gripping her mum’s hand. “How can we stop them? If you and Willy and Billy and Milly can’t, how will we escape?”

 

“There’s only one spell which can stop a wraith,” Mr McIll said. “But it’s all in an ancient language. We brought it with us, but we can’t read it.”

 

Lord Quill had almost reached the doorway. Lily gave a squeak of fear as she looked at his strange eyes. Why didn’t Willy have a potion for this? Why couldn’t any of Billy’s beasts defeat it? Why couldn’t Milly’s spells make the strange wraith turn to smoke? Or Mr and Mrs McIll’s magic knowledge stop him in his tracks? She took the crumpled-up paper from her dad’s hand and wished there was someone who could translate it.

 

And then the strangest thing happened.

 

Lily looked at the swirly squiggles on the page and realised she knew this language. There were scrolls filled with it in Dilly Dotty’s library and she had studied them so she would know where to file them. She pulled out the two broken parts of her wand and began reading the spell. She hoped it wouldn’t matter that the wand was split in two. Perhaps it would work twice as well.

 

As soon as they saw her draw her broken wand, all the family leapt for cover. Willy dived behind a chair. Billy and Mr McIll crouched under the table. Mrs McIll carried Milly and hid behind the open door. Lily didn’t notice any of them, but read the strange words from the sheet of paper.

 

Everyone watched as little fizzles of magic throbbed at the end of both parts of Lily’s wand. Then suddenly, with a force which sent Lily shooting backwards, the two halves of her wand fired a rainbow of light at Lord Quill. Even the guards had to shield their eyes against the brightness.

 

The magic light faded away, and all the family peered down at what lay in the space where Lord Quill had stood. So did the guards. On the ground, curled in on itself with a slightly embarrassed expression, was a little snake.

 

The guards fled from the castle, into The Feral Forest. Billy, who was used to working with animals, picked up Snake Quill and carried him out to the forest, too. They all watched as the former wraith wriggled away into the undergrowth.

 

“That was impressive magic, Lily,” Mrs McIll congratulated her youngest child. “Do you think you could help Milly out of the unfortunate spell you placed on her?”

 

Milly shook her head and picked up her megaphone. “I quite like being this small. It certainly came in handy.”

 

“We make a good team,” Willy added. “When we all work together.”

 

“Even Lily,” Billy said.

 

Mr and Mrs McIll smiled at their children, feeling very proud of each one of them.

 

“Wherever did you learn to read such old writing, Lily?” Mr McIll asked.

 

“At the library,” Lily replied, grinning from ear to ear.

 

“It seems a shame to leave the castle to fall down when The Guild of the Guardians are running out of room at the Spectral Station,” Mr McIll said thoughtfully. “We should invite them here. Twenty towers are too much room for anyone.”

 

So that is what they did. The Guild of the Guardians had fifteen towers of the castle. The largest tower became the McIll home and their children had a tower each. Willy had a laboratory in his tower for mixing potions. Billy used his as a zoo of magical animals. Milly had the smallest tower, but her spells were often seen lighting up the night sky with blue and purple stars.

 

Lily turned her tower into the most magical place of them all. A library.

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