Denee Delgado, age 5, from The Bronx, New York, ran up the steps of the Natural History Museum. The museum had been closed for renovations. Now it was reopening. Superman and Wonder Woman were going to cut the ribbon.

Denee stopped dead in her tracks. Two huge stone lions were staring hungrily down at her. Just for a second, Denee thought the lions were real. “I wish David, Anthony and Andrew were here with me now,” Denee said with a smile. “Don’t worry, Denee,” Wonder Woman said with a laugh. “Those lions won’t hurt you. They are stone. People in Africa carved them 2000 years ago.”

“Wow!” Denee exclaimed. “They sure are fierce looking!”

“The museum is full of really interesting things,” Superman told Denee. “C’mon, it’s time for the museum doors to open.” In the museum’s main hall, Denee saw all the exhibits: dinosaur skeletons and life-sized models of the giant blue whale, the saber-toothed tiger, and the wooly mammoth. Then Denee saw something very strange.

“Look!” Denee cried. “The whale is moving! It’s come alive!”

Sure enough, the blue whale, the biggest mammal ever to live on Earth, was thrashing its giant tail. Frightened people went running and screaming.

“Wonder Woman!” Denee shouted. “Please help the whale! It’s more frightened than the people.” “You’re right, Denee,” Wonder Woman agreed. With all her strength, Wonder Woman lifted the huge animal.

“Wonder Woman will carry the whale out to the harbor where it can swim safely out to sea,” Superman told Denee. “But, I have to get to the bottom of this. What’s going on here?” Superman didn’t know it yet, but Mister Mxyzptlk, the evil little imp from the Fifth Dimension, was having some fun.

Mxy had come to the museum opening, too, and his magic had caused the whale to come alive. But that was not all the mischief he had planned for Superman and Wonder Woman. Denee saw the Tyrannosaurus Rex bones walking across the floor.

“Superman!” Denee shouted.

All over the museum, people were running and screaming. “Help!” they shouted. “Help! Help!” All the museum displays had come to life. Stuffed snakes were crawling on the floor. Tigers and bears were prowling the exhibition hall. The dinosaur skeletons were making their way up one corridor and down the next.

Suddenly, out of the corner of one eye, Denee saw a funny little man scurry across the floor and out of the museum. “Superman, look outside!” Denee called out, pointing to the little man. “Mxyzptlk!” Superman cried. “This isn’t funny, Mxy. Change everything back the way it was. Now!”

“Sorry, Supes. You know that’s not how it works. I’m not fixing anything until someone makes me say my name backwards,” said Mxy with a laugh. And the little imp winked at Denee. Suddenly, Denee heard two blood-curdling roars. The huge stone lions had come alive!

People were screaming for help because the lions hadn’t eaten in 2000 years. They were very hungry. Superman and Wonder Woman rushed to stop the super strong beasts. Mxy grinned at Denee. “I love making Superman and Wonder Woman crazy.”

Denee sat down and thought. How could she make Mxyzptlk say his name backwards? Mxy looked at the destruction he was causing and smiled. “I sure know how to have a good time, don’t I?” he gloated to Denee. “What could be better than this?”

Just then Denee had an idea.

“Well, when I want to have a good time I hang out with David, Anthony and Andrew and Kltpzyxm back in The Bronx, New York,” said Denee. Mxy scratched his head. “What kind of a name is Kltpzyxm?” he asked.

Mxy realized his mistake. “You tricked me into saying my name backwards!” he cried. But it was too late. With a poof, the little imp disappeared back into his own dimension.

Denee looked around. The dinosaurs, the lions, and even the whale—everything was back to normal. “You did it, Denee!” said Superman. “You made Mxy go away!” “Thanks for your help, Denee” Wonder Woman said. “You’re a real hero!”