Thieving Fear — Ramsey Campbell

Something called Charlotte's name that night. Her sister and her cousins, comfortable in their sleeping bags, didn't hear it, but it lured Charlotte to the edge of the cliff, to a secret trapdoor buried beneath dirt and grass. Beyond the trapdoor lay only darkness -- and two unblinking eyes. Charlotte told herself it was only a dream. But something escaped when the door was opened, something that tainted all of them. And now, ten years later, it is drawing them back to that cliff, forcing them to once again peer beyond the trapdoor, to confront what waits for them in the darkness.