Roxy made sure no one was watching her.
Then she sneaked around the school building.
In an instant she was Rocket Girl!
"It's time to find out what happened to Principal Penn," said Roxy.
She blasted off into the sky.
"Look! It's Rocket Girl!" said Mara.
"I wonder where she's going," said Jack.
Terrell looked around.
"Does anyone know where Roxy went?" he asked.
Roxy landed at Police Headquarters.
She found Detective Smith.
He was sitting at his desk, watching something on his computer.
"Are you watching a TV show?" Roxy laughed.
"Aren't you supposed to be solving crimes?"
Detective Smith frowned.
"I'm not watching a TV show.
I'm watching video from a traffic camera."
"I got a call from Mayor Bloom," said Roxy.
"He said Principal Penn disappeared."
"She didn't disappear," said Detective Smith.
"She left town.
In fact, all the teachers from Metro City Elementary School left town. Watch this."
Roxy watched the video from the traffic camera.
The video showed lots of cars and buses driving by.
"Hey! That was Principal Penn!" said Roxy.
"Keep watching," said Detective Smith.
Next Miss Apricot drove by.
Then Mr. Green drove by.
One after another, all the teachers from Roxy's school drove by.
"That's West Street," said Detective Smith.
"It leads out of Metro City and into the mountains."
"So all the teachers drove to the mountains?" asked Roxy.
"I think so," said Detective Smith.
"But it doesn't make any sense.
Why would teachers do that on a school day?
They're supposed to be teaching!"
Roxy watched the video again.
This time she noticed something.
All the teachers were wearing the same star buttons!
And the buttons were glowing.
"I've seen those buttons before!" cried Roxy.
"Mr. Sweeps, the substitute principal, was giving them to all the students!"
"Are you sure about that?" asked Detective Smith.
"That is very suspicious.
We'll have to . . . Rocket Girl?"
In a flash Roxy was back at Metro City Elementary School.
She burst through the front doors.
"Where's Mr. Sweeps?" Roxy demanded.
The hallway was empty.
"Hello?" Roxy called.
No one answered.
Roxy ran into her classroom.
No one was there.
No one was in the principal's office either.
Roxy soon realized the whole school was empty.
"Where did everyone go?" she wondered.
"I'll use my super hearing."
A second later she heard something—something very strange!