And through the avenues shapes were moving. They were the Swamja, and they moved like automatons. They moved in one direction only--away from the ship. As far as Vanning could see the Swamja were pouring through their city. Zeeth said softly, "You are very clever. I still do not understand--" Vanning shrugged, and his voice was tired. "The only way, Zeeth. I broke the tube that shot the North-Fever virus into the upper air. The virus was released within the city, in tremendous quantity. You know how fast it works. And in this strength--" "Yes. It strikes quickly." "Once you've had the fever, you're immune to it ever afterward. So the slaves won't suffer. Only the Swamja. They're getting a dose of their own medicine." "They go north," Zeeth said. "Out of the city." It was true. Far in the distance, the Swamja were pouring toward the north gate, and vanishing through the open valves there. Nothing could halt them. The deadly virus they had created was flaming in their veins, and--they went north. The did not walk; they ran, as though anxious to meet their doom. Through the city they raced, grotesque, hideous figures, unconscious of anything but the terrible, resistless drive that drew them blindly north. Through the north gate, into the pass-- Through the pass--to the lava pits! Vanning's shoulders slumped. "It's nasty. But--I suppose--" "Even the gods must die," Zeeth said. "Yeah.... Well, we've work to do. We'll get food, water, and supplies, and head south for Venus Landing to get help. A small party will do. Then we can commandeer troops and swamp-cats to rescue the slaves from this corner of hell. We can get through to Venus Landing all right--" "Yes, that will be possible--though difficult. Vanning--" Zeeth's eyes hooded. "Yeah?" "Callahan is not here." "What?" The Venusian made a quick gesture. "He awoke when I did. He told me to say that he had no wish to go to prison--so he was leaving." "Where to?" Vanning asked quietly. "Venus landing. He left the ship an hour ago to get food and weapons, and by this time he is in the southern swamps, well on his way. At the Landing, he said, he would embark on a space-ship heading--somewhere." "I see. He'll reach the Landing before we do, then. Before we leave, we'll have to get things in some sort of order." * * * * * Both Hobbs and the girl were moving slightly. Presently they would awaken--and then the work would begin. With the city emptied of the Swamja, it would be easy to organize the slaves, get up a party to march to Venus Landing-- Vanning's mouth twisted in a wry smile. So Callahan was gone. He wasn't surprised. Callahan would never know that the detective had awakened from the crash before any of the others--and had shammed unconsciousness till the fugitive had had time to make good his escape. Vanning shrugged. Maybe he was a damn fool. Getting soft-hearted....