overcrowded. Was this another form of the madness that had driven the people in the Wheel to destroy themselves? That made a convenient explanation, yet Mryna’s mind was too logical to accept it.

One film referred to the founding of the original colony on Rythar, a planet in the Sirian System which had been named for its discoverer. Rythar, according to the film, was one of a score of colonies established by Earth. It was unbelievably rich in deposits of uranium.

That, Mryna surmised, was the name of the sacrificial ore they sent up in the god-cars.

The atmosphere and gravity of Rythar duplicated that of Earth; Rythar should have become the largest colony in the system. The government of Earth had originally planned a migration of ten million persons.

“But after twelve months the survey colony was destroyed by an infection,” Mryna read on the projection screen, “which has never been identified. It is called simply the Sickness. The origin of this plague is unknown. No adult in the survey colony survived; children born on Rythar are themselves immune, but are carriers of the Sickness. The first rescue team sent to save them died within eight hours. No human being, aside from these native-born children, has ever survived the Sickness.”

Now Mryna had the whole truth. She knew the motivation for their madness of self-destruction. It was not insanity, but the sublime courage of a few human beings sacrificing themselves to save the rest of their civilization. They smashed the Guardian Wheel to keep the Sickness there. And Mryna had already [p64] escaped before that happened! She was being hurled through space toward Earth and she would destroy that, too.

If she killed herself, that would in no way alter the situation. The ship would still move in its appointed course. Her body would be aboard; perhaps the very furnishings in the cabin were now infected with the germ of the Sickness. When the ship touched Earth, the fatal poison would escape.

Dully Mryna turned up another frame on the film, and she read what the Earthmen had done to help Rythar. They built the Guardian Wheel to isolate the Sickness. Sealed in metal immunization suits, volunteers had descended to the plague world and reared the surviving children of the colonists until they were old enough to look out for themselves. The answer house had been set up as an instructional device.

“As nearly as possible, the scientists in charge attempted to create a normal social situation for the plague carriers. They could never be allowed to leave Rythar, but when they matured enough to know the truth, Rythar could be integrated into the colonial system. Rytharian uranium is already a significant trade factor in the colonial market. An incidental by-product of the Guardian Wheel is the hospital facility, where advanced cases of certain cancers and lung diseases have been cured in a reduced gravity or by exposure to cosmic radiation.”

Mryna shut off the projection. The words made sense, but the results did not. And she knew precisely why Earth had failed. When they matured—in those three words she had her answer.

And now it didn’t matter. There was nothing she could do. Her ship was a poisoned arrow aimed directly at the heart of man’s civilization.

Mryna had slept twice when the auto-pickup lurched out of the time drive and she was able to see the stars again. Directly ahead of her she saw an emerald planet, bright in the sun. And she knew instinctively that it was Earth.

A speaker under the viewport throbbed with the sound of a human voice.

“Auto-shuttle SC 539, attention. You are assigned landing slot seven-three-one, Port Chicago. I repeat, seven-three-one. Dial that destination. Do you read me?”

Three times the message was