Jack and Mara pushed Roxy into a cell.
Mr. Sweeps smiled. "Now you'll never stop me." He slammed the heavy iron door. Roxy heard him lock it.
Roxy thought about the ring Mr. Sweeps was wearing. "He's using that ring to control everyone. I need to destroy it."
Roxy looked around the cell. "I could break down that door," she thought. "But Mr. Sweeps will hear me. I need a way to sneak up on him."
Roxy kicked at the rock floor to see how hard it was. "I think I have an idea."
Mr. Sweeps was examining a diamond when he heard a crash.
"Rocket Girl is trying to break out of her cell," he yelled. "Everyone, guard the door!"
All the students dropped their tools. They gathered in front of the cell door. Boom! There was a deep rumbling sound. The entire cavern shook.
"As soon as Rocket Girl comes out, capture her!" commanded Mr. Sweeps.
Suddenly—kaboom! Pieces of rock flew everywhere. Roxy blasted through the cavern floor behind everyone.
Mr. Sweeps spun around, but he wasn't fast enough. Whiz-hoo! Roxy fired her eye laser beams. The ring exploded.
"My ring!" cried Mr. Sweeps.
Instantly the students' buttons stopped glowing.
"Where are we?" asked Jack.
"What's going on, Rocket Girl?" asked Mara.
"You were all hypnotized by Mr. Sweeps," answered Roxy. "He isn't really a principal. He was forcing you to mine diamonds here under the school."
"That's right," said Detective Smith, who had just walked into the cavern. "And now Sweeps is going to jail!"
In a flash Rocket Girl disappeared. A moment later Roxy appeared. She was wearing her regular clothes and her star button.
"What happened?" she mumbled, pretending she'd been hypnotized too.
Terrell gave her a suspicious look.
The next morning Principal Penn and the teachers were back at work.
"It looks like things are back to normal," said Mara.
"I'm glad," said Jack. "I'd rather learn than work in that diamond mine."
"You know what else?" asked Mara. "We can go to the zoo! My mom told me our school has money for field trips now."
"Where did the money come from?" Terrell asked.
"Principal Penn is going to sell the diamonds!" said Mara.
"Wow!" said Terrell. "I told you Rocket Girl can do anything. She helped our school get money!"
Roxy didn't say a word.