

Tom and Lily were twins who liked to play outside. One day, they went to the park with their mom. They saw a big slide, a swing, and a sandbox. They ran to the slide and took turns going down. "Whee!" they shouted.
But then, they saw something else. Behind the slide, there was a door. It was small and brown and had a sign that said "Do not enter". Tom and Lily were curious. They wanted to see what was behind the door. They looked at their mom, who was talking on her phone. She did not see them.
"Let's go," Tom said. "Maybe there is a secret place."
"Okay," Lily said. "But be careful. It might be scary."
They opened the door and went inside. It was dark and cold. They saw some stairs going up. They decided to climb them. They held hands and walked slowly. They heard some noises. They sounded like growls and hisses.
"What is that?" Lily asked. "I don't like it."
"Me neither," Tom said. "Maybe we should go back."
But it was too late. As they reached the top of the stairs, they saw a big cage. And inside the cage, there was an unknown animal. It had fur and claws and teeth. It looked angry and hungry. It saw Tom and Lily and roared.
"Help!" Tom and Lily screamed. "Mom!"
Their mom heard them and ran to the door. She saw the animal and the cage and the stairs. She was shocked and scared. She grabbed Tom and Lily and pulled them out of the door. She slammed it shut and locked it.
"Are you okay?" she asked. "What were you doing in there?"
"We were sorry, mom," Tom and Lily said. "We wanted to see the secret place. But it was not fun. It was bad. There was an unknown animal. It was scary."
Mom hugged them and said, "I'm glad you're safe. But you should never go to places you don't know. They can be dangerous. You should always listen to the signs and to me. Do you understand?"
Tom and Lily nodded and said, "Yes, mom. We understand. We won't do it again."
Mom smiled and said, "Good. Now let's go home and have some cookies. And forget about the unknown animal."
But they never forgot. They always wondered what it was and why it was in the park. And they never went near the door again.
