Instruments far in advance of the original telemetering and servomotor devices, had measured temperature, radiation, chemical makeup of atmosphere, minerals, various field effects, measured and catalogued all life, even to its cultural development, then sent back their measurements and evaluations on ultra-high-frequency to ground observers on Earth. He had sent out the first rockets with monkeys, rats, guinea pigs and birds to test the effects of alien conditions on living organisms. No human being had ever survived. They stopped trying. But the Martians had been carrying on a program much the same. They had been frightened. They had sent deadly rockets. The war had begun, a fantastic push-button operation between worlds millions of miles apart. This Earth rocket loaded with three tons of G-agent was what the UN hoped would be the last retaliatory gesture in a number of years of interspatial bickering. For it was also evident now that no Martian could get across space to Earth. Michelson sighed, stepped into the elevator and started home. Home to rest, fish, lie in the sun. Home to Mary who kept him occupied and entertained in his loneliness. But Mary had not been ill. She had not stayed at Lake House either. She had been aboard Michelson's helio, hiding in the luggage compartment. She had the key to Michelson's office and she was there. But her head ached now. She hadn't slept for two days, thinking about what had to be done. Her head ached worse now as the wave directives came again and again, bringing new bursts of coercive pain with any deep emotional hint of possible resistance. Now, in fact, there was doubt in Mary's mind that there was any desire to resist the directives, or if there ever had been. Now even those lingering wonderings about the possibility of doubt brought pain. Better just to act. And it was time. The clock gave her exactly one hour, she knew, to destroy the central building sector, the heart of the giant UN Research Foundation, and also wreck the rocket due to blast for Mars. She had heard Daddy Mike say what time the rocket would blast if he got the G-Agent loaded on schedule, and she knew he had done that. There was little if any caution exercised at the Foundation. It had been well established by years of precedent that humans just didn't sabotage an effort directed at aliens. Especially Martians who, time and time again, had almost brought destruction to earth in innumerable unexpected ways. Added to that was the fact that no Martian could get across the void to take care of it directly, any more than an Earthman could to Mars for a similar purpose. Mary had the advantage of this freedom. But the immediacy with which she could be identified by all the personnel about the Foundation might be a handicap as well as a possible advantage. She would have to exercise extreme caution herself.