"Listen, David. Don't you hear it? A whirring sound, right up above us. Not too near, but—David, I'm frightened. That thing must be following us!"
He had to stand very still and strain his ears for an instant before he caught it. It was unmistakable, but so faint that, under calmer circumstances, he would have been amazed by the acuteness of Janice's hearing. But now there was no room in his mind for amazement. Only horror.
"All right," he said. "It's following us. We might have known that it would. I sensed its rapacity the instant I saw it, and if they kept it from attacking us they must have had a reason."
"What reason, David? Don't try to spare me, if you think you know."
"I don't know for sure. How could I? But I can make a guess that has some ugly implications. It could be a kind of insectlike—"
He hesitated, fighting for control, reproaching himself for his harshness. He was making no attempt to soften the blow and he knew why. He had spoken with a slight edge of angry impatience in his voice because he did not want her to know how profoundly the thought had unnerved him.
It was more than chilling, for there was something diabolically calculated, wholly vicious, about the use of such a horror as a weapon.
A relentlessly pursued man—an escaped prisoner floundering in desperation through a swamp or trapped in a mountain gully—can experience many dreads. But only one that claws at his mind like a sharp-taloned, utterly merciless harpy.
The appeal in Janice's eyes put a quick end to his hesitation. "What could it be, David? Tell me."
"A kind of insectlike bloodhound. A scent-tracking animal can demoralize a fleeing man in a very terrible way, and I'm sure they know it. I think they deliberately kept it from attacking to give us time to escape from the building. Then they let it pick up our scent. They may be planning to prolong the pursuit until we abandon all hope and just wait helplessly for the worst to happen."