He sat up, discovering that he was in a bare room walled with gray plastic, and that he was lying on a pallet of some elastic substance. Under a metallic-looking but soft robe, he was naked. The girl, he saw, bore over her arm a bundle of garments, crimson as the kirtle she herself wore. Her smile was wan. "Hello," she said, in English. "Feel better now?" Vanning nodded. "Sure. But am I crazy? That thing that just went out--" Horror darkened the girl's blue eyes. "That is one of the Swamja. They rule here." "Here? Where's here?" Lysla knelt beside the bed. "The end of the world--for us, Jerry Vanning." "How do you know my name?" "There were papers in your clothes--what was left of them. And--it'll be hard to explain all this. I've only been here a month myself." Vanning rubbed his stubbly beard. "We're on Venus?" "Yes, of course. This is a--a valley. The Swamja have lived here for ages, since before Earthmen colonized Venus." "I never heard of them." "None ever return from this place," Lysla said sombrely. "They become slaves of the Swamja--and in the end they die. New slaves come, as you did." Vanning's eyes narrowed. "Hold on. I'm beginning to understand, a little. The Swamja--those fish-headed people--have a secret city here, eh? They're intelligent?" She nodded. "They have great powers. They consider themselves the gods of Venus. You see--Jerry Vanning--they evolved long before the anthropoid stock did. Originally they were aquatic. I don't know much about that. Legends ... Anyway, a very long time ago, they built this city and have never left it since. But they need slaves. So they send out the North-Fever--" * * * * * "_What?_" Vanning's face grayed. "Lysla--what did you say? The fever's artificial?" "Yes. The virus is carried by microscopic spores. The Swamja send it out to the upper atmosphere, and the great winds carry it all over Venus. The virus strikes very quickly. Once a man catches it, as you did, he goes north. These mountains are a trap. They're shaped like a funnel, so anyone with the fever inevitably heads into the pass, as you did. They are drawn through the mirage, which looks like a wall of rock. No one who wasn't--sick--would try to go through that cliff." Vanning grunted, remembering. "Keep talking. I'm beginning--" "There isn't much more. The victims fall into the pits, and stay there till the fever has run its course. The Swamja run no risks of being infected themselves. After the sickness has passed, it's easy to find the way out of the pits--and all the tunnels lead to this place." "God!" Vanning whispered. "And you say this has been going on for centuries?" "Very many centuries. First the natives, and now the Earthpeople as well. The Swamja need slaves--none live long here. But there is always a supply trickling in from outside."