The splendid capital of Aeria seemed like a city of the dead. Its broad white streets and squares were empty, there were no boats on the lake, and no aerial yachts in the air as there were wont to be at sunrise. The gardens were deserted and silent, even the songs of birds which had welled up from them in a chorus of greeting to the coming sun were now hushed, and the birds themselves were flying restlessly from branch to branch, twittering and calling to each other, frightened sharers in the universal fear. It was not long before Alan learnt from his father the explanation of this strange and mournful change in the life of the valley. A few days after their departure a mysterious epidemic had appeared among the people of Aeria. First the old, then the middle-aged, and then the young had been silently and swiftly stricken down, first in hundreds and then in thousands. There was no sign of physical disease, no apparent source of physical infection, and none of the horrors which characterised the plagues that were decimating the outside world. Those attacked by it went to bed in apparently robust health, and in the morning they were found dead with an expression of perfect peace upon their features and no marks of disease upon their bodies. That was all that was publicly known. There had been, and, as the President told his son, there would be no inquiry into the cause or origin of the epidemic. Whether those who died died voluntarily, or whether the visitation was a merciful release from the torment and terror of the general doom, it was not for those who survived to ask. It was enough for them that the Shadow of Death had begun to steal silently and swiftly over the land of the royal race who had raised the dignity of humanity to a height untouched before in the story of man. They were content to know that their friends and kindred were permitted to die in painless peace rather than forced to writhe out their last hours in torture amidst the conflagration of the world. All day and all night for nearly a month the fires of a hundred crematoria had burned, and day and night the funeral processions had never ceased passing through their gates. The population of Aeria, which had been over a million at the end of July, was now little more than a hundred thousand, and these were hourly dwindling under the mysterious epidemic. Those who had returned in the _Alma_ and the _Isma_ accepted all without question and applied themselves with all their energy to the performance of the solemn duties that remained to them. The work in the caverns of Mount Austral was now almost completed, and the minute calculations which had been made had shown that it would be possible for two hundred and fifty souls to find a refuge in them for ten days if necessary.