“Not sure.” She stopped abruptly, right over the middle. There were four arrows in all, each aimed at the same point—a void about five hundred meters across. She had thought the ice continued over stone in this whole area, but that had just been a trick of the light. Here, it continued downward for so long she saw no reflection. It was just darkness. Maybe if I get closer I can see more. “I think this might be a runway.”