Suddenly he turned to Linda. "Look. See how their flying formation is always the same? They're twenty of them up there all right, and they start to circle the block in a compact mass. But as soon as they strike a point directly above it, they separate. First five, then three, then two, six, one, and three. Always the same order. Do you suppose that might be the combination? A magnetic disturbance issuing from the block in such a way as to prevent the usual twenty-formation and break it up in that fashion?" "Jimmy!" Her eyes lighted. "I think you've got it!" He seized the ancient combination wheel, put his strength to it. Slowly, a fraction of an inch at a time, it began to turn. Jimmy hesitated. [Illustration: He seized the ancient combination wheel....] "I can't read these numerals, if they are numerals," he said. "I don't know where to start." Linda studied the markings. "I think that's the symbol for absolute zero," she said. "Try it anyway." He began to turn the wheel again, counting off the numbers as he watched the irregular formation of _sarkonivals_ above him. "Five, three, two, six, one, three." Twice he tried with no result. The third time there was a dull whirring somewhere in the bowels of the block, and the door slowly swung open. Within, a short passageway ended at another door, equipped with another series of dials. Here Jimmy nodded in satisfaction. "I should be able to crack this." He opened his carry-case, took out the headphones and slipped them on. Linda and Hanley pressed close, watching him. "Hurry," the girl said. "I don't like it here." A voice behind answered her. "No need to hurry, Mr. Starr, alias the Nebula. Just take your time, but be sure you open it." * * * * * They wheeled. Three figures blocked the passage. In the lead, leaning comfortably against the side wall, stood Hamilton Garth, a heat gun leveled before him. Behind him were the two pseudo-I.P. men. "Very nice of you to save us the trouble of locating the figurine cache," Garth said smoothly. "Now all you have to do is open that inner door and then help us carry a load of the images back to our tracto-car. You have nothing to worry about. If you obey orders, no harm will come to you. If you don't, well, don't forget I have a nice ace-in-the-hole. I have only to tell the world that James C. Starr, president of Triplanetary Shipping is the much-wanted cracksman, the Nebula." Jimmy, Linda, and Hanley looked at each other. "Come," said Garth. "This place oppresses me as much as it does you. Get to work." Silently Jimmy adjusted the headphones again and began to move the dials. Five minutes passed. Then he stood back, grasped the handle and pulled the door open. The interior was black, but a click of the torch revealed row upon row of Thro-Pahl images. There were hundreds here, and there must be hundreds more in the lower crypt.