Abby heard the car pull up. A flush of triumph rose in her chest. Bella was home from school! Now the gloating could begin!
Being twins, the sisters spent most of their time trying to out-do each other. Last week, Bella had printed a fake spelling list with misspelt words and snuck it into Abby's book for her to learn.
The week before that, Abby had ruined Bella's show-and-tell.
The battle lines had been drawn. There would be no surrender now!
Abby heard the key in the front door.

"Thing One?" her dad called out. "We're home, honey. How are you?"
"Hi, Dad. I'm—" She faked a cough. "I'm good. Much better."
She had, in fact, had a lovely day in bed. She'd finished reading her Prince Falco book and was partway through the next one, all while Bella was stuck at school.
"Come on, Thing Two," she heard her dad say. "Go check on your sister."
Oh yes, Abby thought. This was better than switching Bella's hermit crabs for plain old seashells. She'd be so jealous! And mad, too; especially if Abby told her how the book ended.

***

"You're in so much trouble," Bella whispered. She made a sad face. "Poor sick you."
Abby frowned.
"No way. He'll never believe you. He'll—"
"Not dad, silly. What, you think I'd dob you in? No." Bella smiled wickedly. "No, this is much better."
She ran off to her own room and came back with their homemade lie detector.
"Test me," she said. She slipped the Velcro around her finger. "Come on. I want to make sure you believe this."
Abby hesitated. She heard her dad out in the kitchen, making afternoon tea for them. She knew Bella was planning something. But what?
"All right," she grumbled. "What's your name?"
"Bella."
"How old are you?"
"Ten." An outrageous lie; the machine buzzed.
"What's your favourite Roald Dahl book?"
"The Witches."
"Did you draw those extra flats on my piano music?"
"No." Buzz.
The lie detector was working.
"Good," Bella declared. "Now listen. We learnt about a creature in school today. It's an infiltrator, Miss McGowan said. It looks like a Chinese dumpling with tentacles, and it kind of feels its way around, reaching out until it grabs you. They're real, Abby." Bella looked her in the eyes. "They're real, and they can kill you. And they're especially attracted to girls who stay home sick. They must already have their eyes on you!!"
Abby stared at her, then down at the lie detector.
"No way," she said. "You're making it up."
"Yes, I am." Buzz.
"But—"
"Infiltrators," Bella repeated. "You won't see them coming, Abs. And you can't run away. They'll feed off you! They'll—"
Just then, their dad arrived with raisin toast and cordial.
"Here we go." He put the tray down and glanced at the lie detector. "What's this, Bell? Confession?"
"Just what I learnt at school today, Dad. You know? Homework and stuff. She won't believe me otherwise."
"Hmm, okay. But come away after that. Abby still needs to rest."
"Sure, Dad."
Bella waited until he'd gone, then turned back to Abby.
"And do you know the best thing?"
Abby shook her head. After a day pretending, now she really did feel a little sick.
"The best thing—" Bella broke off. She peered at the lie detector and waggled her finger. "Oh, this has stopped working." Buzz. "No it hasn't. Good. The best thing about these infiltrators, Abs, is that I've brought one home!"
"What?"
"Mm-hmm." Bella gave her a quick, happy kiss on the cheek. "Just for you. But don't worry. Miss McGowan's told us what to do about them. If you make it through the night, I guess she'll tell you, too."
Bella grinned at Abby, her teeth a pure white flash of triumph. Then she skipped from the room.

***

It didn't make sense, Abby thought. A killer dumpling with tentacles? It had to be a trick!
But, no. Bella had looked so smug. Even without the lie detector, Abby knew she was telling the truth.
She held tightly to her fork over dinner that night. When she had her bath, she soaped herself quickly before scrambling out. She was panicky, she knew, but she couldn't help it! Wherever she turned, she saw dumplings in the shadows. She felt tentacles reaching for her, burrowing into her skin.
In bed, she pulled the covers tight. She kept her reading lamp on, and it was hours before exhaustion drove her to sleep.
Her dreams were nightmares. In one, she heard Bella laugh. When her eyes snapped open, she found herself covered in crawling, suckering dumplings.
Shrieking, she woke up for real.

***

"I think you'd better stay home again, Thing One," her dad said the next morning. "You seem worse today."
"No, Dad. Thanks, but—" she caught Bella's eye. "I should go. I don't want to fall behind."
"We had a really cool science lesson yesterday," Bella chimed in. "Abby's dying to find out about it. Isn't that right, Abs?"
Abby gritted her teeth. Defeat hurt! But what could she do?
"Yes," she admitted. "Really, Dad. I'll be fine."
"Well, if you're sure."
He drove them to school, Bella smirking the whole way.

***

"Abby!" Miss McGowan beamed. "Good to have you back. Here, come on. I've got everything ready. Bella said you wouldn't want to miss out."
She beckoned Abby over to her desk. There was a microscope set up, its lensed eyes tilted towards her. Abby leaned in to look. She saw—
Dumplings. Dumplings with tentacles.
"Germs," Miss McGowan explained. "Bacteria. Infiltrators."
"Infectious diseases cause 50,000 deaths every day," Bella chirped. "Plus," she added, "sleepless nights."
Abby groaned. She felt her shoulders slump. She'd been tricked, all right!
"Amazing," she muttered.
Then, remembering that Bella hadn't finished the Prince Falco book yet, she brightened, just a little. Germ warfare, was it? Maybe she could still get her revenge.
Nodding slowly, she pulled back from the microscope.
"Poor old Prince Falco, right? If only he'd washed his hands more."
Bella gasped. She narrowed her eyes at Abby. And then she grinned.
"Okay, okay. You got me, too!" she allowed, turning back to her own desk. "Well played. But I'll get you next time. You'll see!"