The knock on the door took Shepard-A294 by surprise. He looked up from his work, setting aside his knife and calipers and taking a moment to scrub his hands clean. The knock came again, a sharp, furtive rap that sounded as nervous as it was desperate. Shepard pulled open the door before he could. Both of the colonists shrank back, clearly surprised that he had even opened the door. In the dim evening light he could see that their faces and overalls were covered with black soot. Foundry workers, then. “Yes?” he asked, still wiping down his hands with a grimy rag. “How can I help you?” * *