Spokesman Dorn, the Machine's executive officer, sitting beside Administrator Bradshaw at a transparent desk on the raised platform to Menesee's left, had enclosed the area about the prisoner with a sound block and was giving a brief verbal resume of the background of the situation. Few of the directors in the Tribunal Hall would have needed such information; but the matter was being carried on the Grand Assembly Circuit, and in hundreds of auditoriums on Earth the first and second echelons of the officials of the Machine had gathered to witness the interrogation of the Mars Convict spy. The penal settlements on Mars had been established almost a century earlier, for the dual purpose of mining the mineral riches of the Fourth Planet and of utilizing the talents of political dissidents with a scientific background too valuable to be wasted in research and experimental work considered either too dangerous to be conducted on Earth or requiring more space than could easily be made available there. One of these projects had been precisely the development of more efficient spacedrives to do away with the costly and tedious manoeuverings required for travel even among the inner planets. Work of such importance, of course, was supposed to be carried out only under close guard and under the direct supervision of reliable upper-echelon scientists of the Machine. Even allowing for criminal negligence, the fact that the Mars Convicts were able to develop and test their stardrive under such circumstances without being detected suggested that it could not be a complicated device. They did, at any rate, develop it, armed themselves and the miners of the other penal settlements and overwhelmed their guards in surprise attack. When the next ship arrived from Earth, two giant ore carriers and a number of smaller guard ships had been outfitted with the drive, and the Mars Convicts had disappeared in them. Their speed was such that only the faintest and briefest of disturbances had been registered on the tracking screens of space stations near Mars, the cause of which remained unsuspected until the news came out. Anything which could have thrown any light on the nature of the drive naturally had been destroyed by the deserters before they left; and the few Machine scientists who had survived the fighting were unable to provide information though they were questioned intensively for several years before being executed. What it added up to was that some eighteen thousand sworn enemies of the Machine had disappeared into space, equipped with an instrument of unknown type which plainly could be turned into one of the deadliest of all known weapons.