Suddenly a small splash of sound came from within the palace. A few minutes later two men, dressed in the uniform of the Imperator's guard, emerged. They were followed by four more. And during the next half-hour almost a hundred came from the palace. Some of them carried their belongings in their arms, and all of them were in a hurry. "Something unusual is happening in there," Siggen said. "Whatever it is, it suits our plans," Ostby said. "There can't be many guards left inside. Your men should have little trouble overpowering the remainder." "I don't like it," Siggen said. "But every fear grows worse by not being looked at. Shall we go in?" "Soon," Ostby answered. "Take me to the water-duct first." "It's just around the corner," Siggen replied. "Come on." They turned the corner of the building and Siggen paced off eight steps. "It should be right here," he said. He kicked in the dust until his foot struck a loose brick. "Right," he grunted. Siggen bent and lifted the brick from its loose-fitting hole. "I supervised the job myself to see that it was done right," he said. Ostby could hear a faint gurgle of water coming from the hole. He rolled back the sleeve of his left arm and probed with his fingers until he found the spot he sought. "Cut here," he said. Siggen shook his head disapprovingly but did as he was told. Blood crept out around the knife blade as it did its work. Ostby said nothing. When Siggen had extracted the capsule, he handed it to Ostby. Ostby knelt on one knee and broke the capsule, holding it carefully over the hole in the street. He counted the drops that fell. "Six," he said. "And one more." He shook the broken halves, and dropped them into the water flowing beneath the hole. "That should do it," he commented, with satisfaction. "One drop will effectively impregnate two hundred fifty thousand gallons of water." "I wish I knew what you were trying to do," Siggen said, "but I suppose that you'll tell me in your own good time. Do I send my men in yet?" "Yes, we'd better start. They know that they're to take over the entire first floor and to hold it against all comers?" Siggen nodded and lifted his hand in a prearranged signal. The shadows about the buildings gave up their skulkers, and figures slipped out from every doorway and hiding place and entered the palace. * * * * * Ten minutes passed and not a sound came from within. "It's too quiet," Siggen said. "I don't like it." "We'll go in now," Ostby said. Once in the palace Siggen called over one of his men. "Anything doing?" he asked. "Nothing," the man replied. "The whole place seems deserted." "What do we do now?" Siggen asked, turning to Ostby. "We'll go upstairs. Magogar should be there." "Will I bring along some of the men?" "No," Ostby said. "I have a feeling that we won't need them." Siggen and Ostby went slowly up the stairway. When they reached the room that housed the Brain, Ostby entered first.