A city of the blind! Six millions of people suddenly deprived of sight!

The disaster sounds impossible—a nightmare, the wild vapourings of a diseased imagination—and yet why not? Given a favourable atmospheric condition, something colossal in the way of a fire, and there it is. And there, somewhere folded away in the book of Nature, is the simple remedy.

Such thoughts as these flashed through Hackness\'s mind as he stood under the portico of the Lyceum Theatre, quite helpless and inert for the moment.

But the darkness was thicker and blacker than anything he had ever imagined. It was absolutely the darkness that could be felt. Hackness could hear the faint scratching of matches all around him, but there was no glimmer of light anywhere. And the atmosphere was thick, stifling, greasy. Yet it was not quite as stifling as perfervid imagination suggested. The very darkness suggested suffocation. Still, there was air, a sultry light breeze that set the murk in motion, and mercifully brought from some purer area the oxygen that made life possible. There was always air, thank God, to the end of the Four Days\' Night.

Nobody spoke for a time. Not a sound of any kind could be heard. It was odd to think that a few miles away the country might be sleeping under the clear stars. It was terrible to think that hundreds of thousands of people must be standing lost in the streets and yet near to home.

A little way off a dog whined, a child in a sweet refined voice cried that she was lost. An anxious mother called in reply. The little one had been forgotten in the first flood of that awful darkness. By sheer good luck Hackness was enabled to locate the child. He could feel that her wraps were rich and costly, though the same fatty slime was upon them. He caught the child up in his arms and yelled that he had got her. The mother was close by, yet full five minutes elapsed before Hackness blundered upon her. Something was whining and fawning about his feet.

He called upon Grimfern, and the latter answered in his ear. Cynthia was crying pitifully and helplessly. Some women there were past that.

"For Heaven\'s sake tell us what we are to do," Grimfern gasped. "I flatter myself that I know London well, but I couldn\'t find my way home in this."

Something was licking Hackness\'s hand. It was the dog Kim. There was just a chance here. He tore his handkerchief in strips and knotted it together. One end he fastened to the little dog\'s collar.

"It\'s Kim," he explained. "Tell the dog \'home.\' There\'s just a chance that he may lead you home. We\'re very wonderful creatures, but one sensible dog is worth a million of us to-night. Try it."

"And where are you going?" Cynthia asked. She spoke high, for a babel of voices had broken out. "What will become of you?"

"Oh, I am all right," Hackness said with an affected cheerfulness. "You see, I was fairly sure that this would happen sooner or later. So I pigeon-holed a way of dealing with the difficulty. Scotland Yard listened, but thought me a bore all the same. This is the situation where I come in."

Grimfern touched the dog and urged him forward.

Kim gave a little bark and a whine. His muscular little body strained at the leash.

"It\'s all right," Grimfern cried. "Kim understands. That queer little pill-box of a brain of his is worth the finest intellect in England to-night."

Cynthia whispered a faint good-night, and Hackness was alone. As he stood there in the blackness the sense of suffocation was overwhelming. He essayed to smoke a cigarette, but he hadn\'t the remotest idea whether the thing was alight or not. It had no taste or flavour.

But it was idle to stand there. He must fight his way along to Scotland Yard to persuade the authorities to listen to his ideas. There was not the slightest danger of belated traffic, no sane man would have driven a horse in such dense night. Hackness blundered along without the faintest idea to which point of the compass he was facing.

If he could only get his bearings he felt that he should be all right. He found his way into the Strand at length; he fumbled up against someone and asked where he was. A hoarse voice responded that the owner fancied it was somewhere in Piccadilly. There were scores of people in the streets standing about talking desperately, absolute strangers clinging to one another for sheer craving for company to keep the frayed senses together. The most fastidious clubman there would have chummed with the toughest Hooligan rather than have his own thoughts for company.

Hackness pushed his way along. If he got out of his bearings he adopted the simple experiment of knocking at the first door he came to and asking where he was. His reception was not invariably enthusiastic, but it was no time for nice distinctions. And a deadly fear bore everybody down.

At last he came to Scotland Yard, as the clocks proclaimed that it was half-past one. Ghostly official voices told Hackness the way to Inspector Williamson\'s office, stern officials grasped him by the arm and piloted him up flights of stairs. He blundered over a chair and sat down. Out of the black cavern of space Inspector Williamson spoke.

"I am thankful you have come. You are just the man I most wanted to see. I want my memory refreshed over that scheme of yours," he said. "I didn\'t pay very much attention to it at the time."

"Of course you didn\'t. Did you ever know an original prophet who wasn\'t laughed at? Still, I don\'t mind confessing that I hardly anticipated anything quite so awful as this. The very density of it makes some parts of my scheme impossible. We shall have to shut our teeth and endure it. Nothing really practical can be done so long as this fog lasts."

"But, man alive, how long will it last?"

"Perhaps an hour or perhaps a week. Do you grasp what an awful calamity faces us?"

Williamson had no reply. So long as the fog lasted, London was in a state of siege, and, not only this, but every house in it was a fort, each depending upon itself for supplies. No bread could be baked, no meal could be carried round, no milk or vegetables delivered so long as the fog remained. Given a day or two of this and thousands of families would be on the verge of starvation. It was not a pretty picture that Hackness drew, but Williamson was bound to agree with every word of it.

These two men sat in the darkness till what should have been the dawn, whilst scores of subordinates were setting some sort of machinery in motion to preserve order.

Hackness stumbled home to his rooms about nine o\'clock in the morning, without having succeeded in persuading the officials t............