The buzzing seemed to go on interminably as he hovered between sleeping and waking. On and on and on, with absolutely no letup. Then, abruptly, it ceased. There was a faint swishing sound and something solid thudded into the hardwood directly above him. With a startled cry Corriston leapt from the cot, caught the iron edge of the bed-guard to keep from falling, and stared up in horror at the shining expanse of wall space overhead. The cell was in almost total darkness. But from the barred window opposite, a faint glimmer of light penetrated in a diffuse arc, just enough light to enable him to make out the quivering stem of the barb. It _was_ a barb. This was so beyond any possibility of doubt. It had lodged in the hardwood scarcely a foot above his cot and it was still quivering. Cold sweat broke out on Corriston's palms as he realized how close death had come, and how almost miraculous had been his escape. Had he raised himself to slap at the "mosquito" the barb could just as easily have buried itself in his skull. Corriston hesitated for an instant, his eyes on the barred window and the faint glow beyond. Then his gaze passed to the wall switch. He decided against switching on the light immediately. He stooped low and moved quickly to the window, taking care to keep his head well below the sill. For a moment he listened, his every nerve alert. There was no stir of movement in the darkness beyond the sill, nothing at all to indicate that someone was crouching there. Finally, with an almost foolhardy recklessness, he raised his head and stared out between the bars. He could see right across to the wall opposite. The wall was less than eight feet away, and the space between the wall and his cell appeared to be unoccupied. This did not surprise him. It was utterly silly to think that a man intent on willful murder would have lingered for any great length of time in so narrow a space. After having shot his bolt, his immediate concern would have been to get away as quickly as possible. No, definitely, the man was gone, and if he had more barbs to release he would choose another time and place. Even then Corriston did not switch on the light. He had no particular desire to examine the wood-embedded barb in a bright light. He could see it clearly enough from where he stood. It was exactly like the barb which had sealed the lips of that blabbermouth Clakey. Corriston went back to his cot and sat down. He told himself it would be highly dangerous to leave the cell and give the killer another chance. He had saved himself by refusing to slap a non-existent mosquito. But in the shadows of the Station there would be no mosquitoes--non-existent or otherwise. The killer would simply crouch in shadows, await his chance, and take careful aim.