Most of the diners had gone back into the hotel. They had stood for an indecisive moment, looking this way and that. Baffled by the disappearance of the alien beings, they had straggled inside one by one. Few words were spoken among them, since each was mentally busy forming a theory to explain the occurrence. Two of those who dallied behind, both youths, had already come up with explanations, and were telling them to each other with great zealousness and many a gesture. "Listen," said Bicks. "I tell you they used invisibility belts. Something got out of whack with them just when those beings entered the dining hall and we saw them. They high-tailed it, working on the belts as they ran. By the time they reached the street, they had them repaired. Zap!--just like that, they were invisible again and we lost them. It's simple." "It's too simple," said Paul scornfully. "Why would both belts conk out at once? My idea is that they came out of another dimension. Looking Earth over for conquest, maybe. But when they found themselves in the hotel surrounded by a lot of people--we'd be monsters to them, you know--they got panicky and ran. Then they recovered, switched on whatever gadget they use, and returned to their own dimension. I'd bet my life that's the real answer." Bicks didn't agree. He ridiculed the theory, improvised a joke about it. His companion answered hotly. Immersed in argument they walked slowly up the hotel steps. Both glanced briefly at the large banner stretched above the door. The banner which read: WELCOME TO THE CHICON II! 10th WORLD SCIENCE-FICTION CONVENTION