It came just as he reached the bunkhouse steps—a pistol shot, sharp and snapping. There was another and another still, and out of the tail of his eye he glimpsed indistinctly the swift dash of some figures past the rear of a building across the road. Racing up the steps, Steve panted out his message. In a moment more the piercing wail of a siren screamed shrilly through the night, followed quickly by the dull throbbing of machinery.