Exit a Dictator by E. Phillips Oppenheim

Alexander, a man who had never known fear, lay panting upon his bed in the early hours of the following morning, a new, unanalysable sense of terror chilling his blood. He was breathing in short, laboured gasps, at the back of his head was a feeling of giddiness, a strange lack of control which he had never before in his life experienced. A sense of terrible weakness and depression was upon him. He had an almost overmastering impulse to close his eyes, lean back amongst his pillows and court sleep, forgetfulness, to step out of the world of action the nearest and the easiest way. The thing came in waves, followed by faint reactions during which his will made frantic efforts to reassert itself. It was during one of these that he realised what was happening and with a mighty effort plunged into battle, a battle with himself. He sat up in bed and turned on the light. He looked around him in amazement. All three portholes were firmly closed. There was a slight mist in the room, a curious sickly and yet not altogether unpleasant odour, and a faint hissing sound in his ears. He crawled out of bed and staggered to his feet. By the side of the lamp which he had just turned on was an ordinary medicine bottle, from the cork' of which protruded a tube of rubber. Something in the bottle was bubbling. Out of the end of the tube came little spirals of the grey mist. He laid his thumb upon the bell. Almost immediately, he felt a curious desire to withdraw it and crawl back to bed. He set his teeth. His thumb remained rigid. In the background of his mind he knew that there was something to be done. He began to ask himself furiously what it was--something outside the room--something to be done even while this nightmare laid its clammy fingers about him. A knock at the door. He called out, although he failed to recognise his own voice.

"Come in!"