The Strange Noise

Every night at 11:00 PM, Lisa hears a strange noise. It comes from the wall in her bedroom. Tap. Tap. Tap. "What is that?" she thinks. She listens carefully. The tapping is regular, like a clock. The next day, Lisa asks her neighbor. "Do you hear a strange noise at night?" Her neighbor shakes his head. "No, I don't hear anything." Lisa decides to investigate. She gets a flashlight and goes to the basement. The noise is louder down here. She follows the sound to a corner. Behind some old boxes, she finds a small pipe. The pipe is dripping water. Drip. Drip. Drip. The sound travels through the wall to her bedroom. That's the mystery noise! Lisa calls a plumber. He fixes the pipe in one hour. That night, Lisa sleeps in perfect silence. "Mystery solved," she says with a smile.