Спільний звук

It was exactly 12:00 AM when Daniel heard the sound. Knock… knock… He opened his eyes slowly. His room was dark. Everyone in the house was asleep. Knock… knock… The sound was coming from his wall. “That’s impossible…” he whispered. He stood up and walked closer. His heart was beating fast. Suddenly… A small line of light appeared on the wall. Then… a door formed. A real door. Daniel froze. “Should I open it…?” he said quietly. The knocking stopped. No