The whistle blew.And suddenly, everyone ran.“Move! Move! Move!” Daniel shouted beside me.I pushed myself forward, my shoes hitting the dusty ground as fast as they could. Around us, students from different classes raced toward the first checkpoint.It was our school's annual Adventure Challenge.The rules were simple: follow the clues, complete the challenges, collect the team's flag, and return to the school before the other teams.Our team had one goal.Win.Daniel ran beside me, carrying our map.“Are we still going the right way?” I asked.He quickly looked at the map.“I think so.”“You think?”“Don't worry about it!”“That doesn't make me feel better!”He laughed.We continued running until we reached the first checkpoint.A teacher handed us an envelope.“Your first clue,” she said.Daniel opened it.He read:“When the road ends, follow the sound of running water.”Daniel looked toward the forest.“That's easy.”We followed the narrow path into the trees.At first, everything seemed normal.Birds flew between the branches. The wind moved through the leaves, and sunlight passed through the trees in thin golden lines.Then we heard it.Water.We followed the sound until we reached a small stream.“What's next?” I asked.Daniel looked at the map.“There's supposed to be a bridge somewhere around here.”We walked along the stream.Then we saw it.An old wooden bridge stretched across the water.It looked like it hadn't been used in years.A red flag was hanging from the other side.Daniel smiled.“There it is.”He stepped forward.I grabbed his shoulder.“Wait.”He turned.“What?”I pointed at the bridge.One of the wooden boards was broken.Daniel stared at it.“Okay... maybe we should be careful.”We slowly stepped onto the bridge.CREAK.The entire bridge shook.We froze.“Don't move,” I whispered.Daniel looked down.The water was flowing beneath us.Then—CRACK!A wooden plank broke behind us.We turned around.The path back was blocked by a fallen branch.Daniel looked at me.“That's not good.”Suddenly, we heard something from the other side of the bridge.A sound.Three short knocks.Knock. Knock. Knock.We looked at each other.“What was that?” Daniel whispered.I didn't answer.Then we heard it again.Knock. Knock. Knock.But this time, it came from underneath the bridge.Daniel slowly looked down.His face changed.“What?”He pointed.There was something attached beneath the bridge.A small black box.And on the box was a symbol neither of us had ever seen before.A red circle with a lightning-shaped line through the middle.Daniel reached toward it.“Don't touch that.”He stopped.Before either of us could move, a loud whistle came from the forest behind us.We turned.Someone was standing between the trees.Watching us.Then the person disappeared.Daniel looked at me.“Did you see that?”“Yes.”“Who was it?”“I don't know.”The bridge suddenly shook again.We both grabbed the ropes.“Forget the box!” Daniel shouted. “Run!”We sprinted across the bridge.The moment we reached the other side, the old bridge made another loud cracking sound.We turned around.The bridge was still standing.But the black box was gone.Daniel stared at the empty space beneath it.“Where did it go?”I looked toward the forest.The person we had seen was nowhere to be found.Then I noticed something on the ground.A small piece of paper.I picked it up.There were only four words written on it:“YOU SHOULD NOT BE HERE.”I looked at Daniel.The competition suddenly didn't feel like a competition anymore.