Megosztott hang

I moved into a cheap old house no one wanted. The first night at 3:17 AM I heard knocking from inside the wall. Knock. Knock. Then a whisper: "Open." The wall started to move, like it was breathing. A pale hand pushed through, followed by a twisted face with wide eyes and a broken smile. "Why didn’t you open?" it said. I ran and never came back. But every night at 3:17 I still hear the knocking. Now it’s not in the wall. It’s behind me.