When they were but a little way from their destination Ralph became conscious of a faint hissing sound close behind them. Twice he glanced over his shoulder, but the roadway at that hour—it was just before noon—was deserted.
Yet the sibilant sound persisted, seeming to be getting closer and closer, like some persevering insect about to alight.
Alice apparently heard nothing, or perhaps she thought it merely one of the noises of the street, for she chattered on in the gay animated fashion that was one of her charms, oblivious to the fact that the man at her side was so preoccupied that he scarcely replied to her.
For Ralph had now satisfied himself that there was nothing anywhere around them which could cause that untiring pursuant hiss. Then from what secret invisible source did it emanate—and why?
To the scientist, accustomed to explaining the unexplainable, it was ominous—menacing—
Again he turned to look behind him, along the deserted way, and at that moment he heard a stifled cry from the girl beside him. He whirled to face her, and faced—nothing! He was alone in the empty street!
Unbelieving, doubting the evidence of his eyes, he stared about him, too astounded for the moment, by this mystifying and amazing disappearance to think collectively.
Above him the sun shone in a clear blue sky, before and behind him stretched the still roadway. Then he was aware of the silence, the deadly quiet. For the hissing had receded into nothingness, and with it, Alice.
As the full force of the catastrophe struck him, something akin to panic seized him. Danger to himself he could have faced with the calm courage of a brave man, but this unseen and unexpected blow from an invisible source aimed at the girl so close and dear to his heart smote him with a chill terror that for an instant held him powerless in its grip.
That he should have been careless when she was in danger—but this was no time for self-reproaches. To act, and to act at once—that was vital.