Under the threat of Rick's rifle, then Scotty's and Zircon's, the lamas fell back until the group stood alongside the Black Buddha, looking into the cave. There were torches everywhere! And cooking fires. Rick's first thought was that they had returned in the midst of a religious celebration. And then he saw Sing. The Chinese guide ran to them, his face split by a wide grin. "You came," he exclaimed happily. "We were about to tear the mountain down, stone by stone! Where is the Indian boy?" Chahda came from behind the statue, herding the Tibetans who carried Long Shadow, Ko, and the Nansen bottles. Sing turned and yelled. The lamas broke into cries of approval at the sight of Chahda. Several of them ran to him and pressed his hand. He was a favorite, obviously. "They came to help when I told them the Indian boy was in danger," Sing explained. "We were ready to start digging holes to find the caverns, because we couldn't find the door." He eyed Long Shadow curiously and grinned at the sight of Ko. "Should I get my frying pan again?" he asked. "Might be a good idea," Rick said. "My boss not come yet?" Chahda asked. Sing clapped hands to his head in a gesture of self-annoyance. "I forgot. A letter came. One of the consulate guards, a Chinese who knows this part of the world, brought it from Chungking. It may be from Mr. Bradley, because it came originally from Hong Kong." Zircon took the envelope while Rick, Scotty, and Chahda looked over his shoulder. The envelope was marked for delivery from Hong Kong to Chungking via diplomatic pouch. It was addressed to Zircon, with the note, "Urgent. Forward by messenger." Bradley's initials were signed to it. The scientist ripped the envelope open and, looking around to be sure Long Shadow and Ko were out of earshot, he read: "'Have all the answers except the source. When you find it, destroy it if possible. If you get Long Shadow or Worthington Ko, don't bother bringing them back to Hong Kong, if they're still alive. Leave them at Korse Lenken. Cable me from Chungking when you return.'" It was signed "Bradley." "I like his confidence in us," Zircon remarked. "Not 'if,' but 'when.'" "My boss does not know what it means to fail," Chahda said. "I can see one failure," Zircon remarked. "How does one destroy a body of water?" Scotty's forehead wrinkled thoughtfully. "Couldn't we stir it up? The heavy water is all at the bottom. If we could give it a stir, the heavy stuff would mix with the rest." "But would maybe settle right back," Chahda objected. "Not for a few thousand years," Zircon said. "A good idea, Scotty. Do you happen to have a spoon seven hundred feet long?" Scotty grinned. "Yes. Mr. Ko supplied one." He reached into his pocket and pulled out a grenade. "These will do the best job of stirring that black cup of tea that you've ever seen." "Capital!" Zircon exclaimed. "They'll do perfectly, Scotty." He looked at the boys. "Who wants to go back?"