THE FOUR CORNERS RITUAL - There Were Only Four People in the Room... Until the Fifth Clap

Turn off the lights. Close the door. Stand in your corner. And whatever you do... don't look behind you. There are four corners in the room. The counting begins. One. Two. Three. You walk to the next corner. Facing the wall. Following the rules. Then the signals begin. One knock. One clap. One footstep. One touch. Four players. Four signals. Exactly as expected. Until one night... someone hears a fifth. A fifth clap.