On "Police Operation" by H. Beam Piper (12,438 words) ***

Something is loose and killing farm animals, slashing them to pieces. The folks around the valley are after it. And one man has more at stake than all the others. He knows what the thing is. What is supernatural? Are people who claim to see UFOs seeing something from another planet? Are they seeing something we make right here on Earth? This story has its own answer, and it's no X-Files conspiracy. Read the story here at Project Gutenberg, or listen to it here (part 1), here (part 2), and here (part 3), at Project Gutenberg Audio.