The girls started inspecting the tree’s lower branches to check for damage.

“I’ll check the fruit,” Littlehorn said. She concentrated hard, and with a wave of her horn an apple floated down from the top of the tree. It landed on the ground in front of her. Littlehorn nudged it with her horn and then froze.

“What’s wrong?” Summer asked. As she watched, a lump rose on the apple’s rosy skin. Then it burst — and out came the head of a big, purple, black-spotted caterpillar.

“That’s a slime caterpillar!” Trixi cried. “They usually live on the other side of the kingdom, in the grounds of Queen Malice’s horrible Thunder Castle. The more they eat, the bigger they get!”

The funny-looking creature nosed around in the warm air and stuck its tongue out at the girls before burrowing back out of sight.

“Yuck!” gasped Ellie, stepping backward into Littlehorn, who stumbled and knocked over a basketful of apples.

The fruit spilled out onto the ground, and more caterpillars fell out with it.

“Ugh, they’re horrible!” said Jasmine, looking at one of the slimy creatures, which was chomping on an apple enthusiastically.

Summer watched a caterpillar as it swallowed a big chunk of apple and then burped loudly. “They’re just hungry,” she said kindly.

“Summer, you’d love any animal — no matter how disgusting it is!” Ellie teased her friend.

“Let’s see if I can get rid of them,” said Trixi, guiding her leaf down next to the nearest caterpillar and tapping it with her ring. She chanted:

“You greedy things aren’t wanted here.

This spell will make you disappear!”

Nothing happened.

“Queen Malice’s magic is too strong for me.” Trixi sighed.

The girls exchanged dismayed looks.

“We’ll have to destroy the thunderbolt,” Silvertail said. “I’ll get my strongest unicorns and we’ll pull it right out of the ground.”

“It’s no use,” Trixi told her. “In order to get rid of the thunderbolt we’ll have to break Queen Malice’s spell.”

“What will we do if the caterpillars hurt the tree?” Littlehorn asked. She was standing beneath the Great Apple Tree, gazing unhappily at the caterpillars, who were wriggling about among the spilled apples and chomping happily. A big, sparkling teardrop rolled from one of her eyes. Where it splashed onto the grass, a tiny flower started to grow. “If the valley turns back the way it was, we’ll have nowhere to go.”

Silvertail looked at her daughter. “Why don’t you go and practice for the race, Littlehorn?” she said kindly. “It’ll take your mind off things. And you girls could all go and watch,” she suggested, turning to Ellie, Summer, and Jasmine. “Maybe you’ll be able to find more clues about what Queen Malice is up to, and how to stop her. My orchard keepers are the best gardeners in the Secret Kingdom. I’m sure they can take care of the caterpillars until we find out how to break Malice’s spell. I’ll stay here to help them.”

“And I’ll put a holding spell around the tree so that the caterpillars can’t spread to the rest of the orchard,” Trixi told them.

“Yes, let’s go to the practice area,” Summer said to Littlehorn comfortingly, stroking her hand along the unicorn’s coat. “We’ll probably come up with an idea there.”

The little unicorn nodded bravely and led the way out of the apple orchards, toward the racetrack. As they walked into the gardens, the girls looked around them anxiously, trying to spot any other signs of Queen Malice’s mischief.

Summer noticed that Littlehorn was looking down at her hooves as she walked, with a worried expression on her face.

“Why don’t you tell us about the Golden Games?” Summer asked to distract her.

The little unicorn looked happier at the thought of the afternoon’s fun.

“Well, there’s the Great Race, of course,” she said. “And there are lots of other games and sports, and feats of unicorn magic, too.”

“That sounds wonderful.” Summer smiled as the girls reached the racetrack. It circled a playing field and a small hill, which was already crowded with unicorns watching the others practice. The track was covered with grass that grew in colored lines to show the runners where to go.

“What game are they playing?” asked Summer, pointing to some unicorns on the big field inside the track, who were leaping up at shining golden hoops that floated magically in the air and catching them on their horns.

“That’s Unicorn-Horn Hoopla,” said Littlehorn proudly. “And over there, they’re playing a game of Runaway Rounders.”

The girls watched a team of unicorns who were using their horns to hit a bright red ball. Every time the ball hit the ground it sprouted little legs and tried to run away from the fielders.

“Look, there’s King Merry!” said Ellie, pointing excitedly. The little king looked very sharp in his royal robes, except that he had bits of paper sticking out of all his pockets, and ink stains on his cloak.

He was pacing up and down beside the track, scratching his head so hard that his half-moon spectacles were knocked almost off his nose.

“He looks worried,” said Trixi. “I’d better see if he’s okay.”

Summer, Ellie, and Jasmine hurried over to the king, who was muttering to himself absentmindedly.

“Now, let me see,” he said. “It is your honor to address me today… . Dearie me, no, that’s not right. I mean, it is my honor to address you tomorrow… . Oh my goodness, no, that won’t do either.”

“Is he practicing his welcome speech?” Summer whispered to Trixi.

“I think he must be,” replied the pixie. “He’s not very good at remembering his lines!”

The king stopped pacing and patted his pockets as if he was looking for something. Trixi flew forward and conjured up a large spotted hanky, magicking his robes clean and tidy at the same time.

“Hello!” King Merry said cheerfully. “Girls, how nice to see you again. Are you here for the games?”

“Not quite,” Ellie explained. “The Magic Box has brought us here. There’s a thunderbolt in the roots of the Great Apple Tree.”

“And it’s already causing trouble,” said Jasmine. “There are horrible slime caterpillars attacking the tree.”

“How terrible!” said the king. “Do you have a plan to get rid of the thunderbolt?” He looked at the girls hopefully.

“Not yet,” Ellie admitted. “But we’re working on it.”

“Wow, look at her go!” Summer said, pointing at Littlehorn, who was now racing around the colored track with five other young unicorns. “She’s so fast!”

In spite of her worries, Summer couldn’t help smiling as the beautiful creatures galloped along, urging one another on. “We won’t let the unicorns down,” she promised King Merry.

But just as the words left her mouth, something dreadful happened!

Right in front of the racing unicorns, a cluster of long green weeds broke through the surface of the track. The thick stalks immediately began to grow, snaking out across the grass in all directions. The nasty plants slithered out and tangled themselves in the legs of the running unicorns. Four of the runners got so tripped up they fell horn over hoof. Littlehorn only escaped by leaping high into the air as a stalk tried to grab her tail.

“What on earth are those?” cried Ellie as one of the weeds burst up through the ground at Jasmine’s feet. Ellie and Summer grabbed it and pulled as hard as they could, but the wriggling stem slipped out of their hands and kept on growing.

“It must be because of the Great Apple Tree!” Trixi cried. “With the caterpillars eating the fruit, the tree must be getting weaker. And since its magic is fading, the horrible weeds are coming back to Unicorn Valley! Quick, head for the hill!”

Everyone started running up the hill, but new vines began springing up all around them, and they had to dodge the stalks as they ran. The girls and unicorns managed to scramble to the top of the hill quickly, but King Merry lagged behind. He was out of breath, and Trixi had to help push him up the slope. They had almost reached the girls when a weed curled around King Merry’s foot and tripped him.

Ellie dashed down to help him, but one of the vines wound around her waist. As Summer and Jasmine watched in horror, the vicious vine started pulling her down the hill!