The next morning Ben and Sid arrived at the show bright and early.
"First, we have to clean some cages," Ben said.
He led Sid over to some empty chairs.
"You can wait here. I'll do the cleaning myself, just in case you're allergic to anything.
When I'm done, I'll get you, and we can visit the rats."
"Sounds good." Sid nodded.
"Cleaning cages doesn't sound fun anyway."
"It's not," Ben agreed.
About an hour later, the brothers approached the rodent area.
Almost instantly, green spots appeared on Sid.
He tried holding a hairless mole rat, but even that one caused green spots to appear.
Finally, Sid threw up his hands in frustration.
"We've tested dogs, lizards, dragons, and now rats!"
He looked like he was about to cry.
"Maybe we should try snakes after all, even though I hate them."
"Maybe," Ben said. But he wasn't crazy about a pet snake either.
"Look, there's Waldo. He's got Oswald with him." Ben waved his friend over.
"Hey, guys!" Waldo smiled as he hurried over with his owl.
He held up Oswald's cage.
"I think I've got this guy's problems worked out.
He's been following all my commands today."
"But . . ." Sid stared at the cage and blinked.
"That cage is empty, Waldo."
Ben and Waldo chuckled.
"It's not empty," Waldo said, clapping a hand on Sid's shoulder.
"Oswald is an invisible owl," Ben explained.
"He can make himself disappear."
"Wow, he's invisible? Cool!" Sid pressed his face right up against the bars of the cage.
Then he turned around to flash a grin at Ben.
"Look! No spots! We can get an invisible owl for a pet!"
"Unless your spots are invisible too," Ben said.
Sid scratched his head. "Oh . . . good point."
"Watch this. I'll make Oswald visible," Waldo said.
He let out two sharp whistles.
They waited.
"I still don't see him," Sid said.
Waldo frowned and whistled again.
But again nothing happened.
Ben tried whistling next.
Still there was no sign of the owl.
"Maybe he's asleep." Waldo reached into the cage.
"Hey, Oswald, wake up!" He felt around for a moment before turning back to Ben.
"Uh-oh." He sounded worried. "I think Oswald escaped."
"What?" Ben stared at Waldo in disbelief. "Are you sure?"
"Yes!" Waldo nodded. "He's not in his cage!"
"When was the last time you saw him?" Sid asked.
"Er . . . I mean, you know what I'm trying to ask."
"I was practicing with him in the library," Waldo said.
"He was visible when I put him back in the cage.
Then I went to the cafeteria for a snack.
Maybe he escaped somehow then."
"Did you lock the cage?" Ben asked.
"I thought I did," Waldo said with a shrug.
"But maybe I forgot or the latch was loose or something."
He held his face in his hands. "This is terrible."
Ben took a deep breath, trying to stay calm.
"He's probably still inside the school building. Let's start looking for him."
"How do you look for an invisible owl?" Sid asked.
"I have no idea," Ben said.
"But we're about to figure that out. Come on, Waldo."
The wizard just stood there.
"What if he flew outside?" Waldo moaned.
"If that happened, he'll be lost forever!"
"We haven't even looked yet, Waldo," Ben said.
"And now we're losing precious time."
Waldo nodded, and the three monsters began searching, whistling and calling for the missing owl.
They searched all over the gym and then looked in some classrooms.
Next they checked the library and hallways.
"I told you this was hopeless," Waldo said.
"There's no way to find an animal who's invisible!"
Ben stayed quiet, and so did Sid.
It was hard to argue with Waldo's point.
Then Ben spotted Miss Bungle waving madly at him.
"There you are, Ben! I've been looking for you.
You were supposed to sweep the bunny rabbits' area.
You didn't show up."
"Oh, right. Sorry, Miss Bungle!" Ben replied.
"Waldo's owl . . . um, well, we had a small emergency."
"You should get going," Miss Bungle said, glancing at her watch.
"You don't want to miss the pet tricks show when it starts."
"Go ahead, Ben," Waldo said.
"Sid and I will keep looking for Oswald. You can catch up with us later."
Ben nodded. It probably wouldn't take him long to sweep the bunny rabbits' area.
After that he could rejoin the hunt for the missing owl.
A chill rippled along his spine as he remembered the owl's sharp beak and talons.
He hoped Oswald wasn't busy hunting right now!