"Thank heaven!" gasped Tom, as he pushed on. A moment later, climbing over the rusted rails on which the mine cars had run with their loads of salt, they staggered into the open. They were free--under the silent stars! "And now, if we can only find the airship," said Tom faintly, "we can--" "Look there!" whispered Ned, pointing to a patch of deeper blackness that the surrounding night. "What's that." "The Falcon!" gasped Tom. He started toward her, for she was but a short distance from a little clump of trees into which they had emerged from the opening of the salt mine. There, on the same little plane where they had landed in her was the airship. She had not been moved. "Wait!" cautioned Ivan Petrofsky. "She may be guarded." Hardly had he spoken than there walked into the faint starlight on the side of the ship nearest them, a Cossack soldier with his rifle over his shoulder. "We can't get her!" gasped Ned. "We've got to get her!" declared Tom. "We'll die if we don't!" "But the guards! They'll arrest us!" said the exile. An instant later a second soldier joined the first, and they could be seen conversing. They then resumed their pacing around the anchored craft. Evidently they were waiting for the escaped prisoners to come up when they would give the alarm and apprehend them. "What can we do?" asked Mr. Damon. "I have a plan," said Tom weakly. "It's the only chance, for we're not strong enough to tackle them. Every time they go around on the far side of the airship we must creep forward. When they come on this side we'll lie down. I doubt if they can see us. Once we are on hoard we can cut the ropes, and start off. Everything is all ready for a start if they haven't monkeyed with her, and I don't think they have. We've got room enough to run along as an aeroplane and mount upward. It's our only hope." The others agreed, and they put the plan into operation. When the Cossack guards were out of sight the escaped prisoners crawled forward, and when the soldiers came into view our friends waited in silence. It took several minutes of alternate creeping and waiting to do this, but it was accomplished at last and unseen they managed to slip aboard. Then it was the work of but a moment to cut the restraining ropes. Silently Tom crept to the motor room. He had to work in absolute darkness, for the gleam of a light would have drawn the fire of the guards. But the youth knew every inch of his invention. The only worriment was whether or not the motor would start up after the breakdown, not having been run since it was so hastily repaired. Still he could only try. He looked out, and saw the guards pacing back and forth. They did not know that the much-sought prisoners were within a few feet of them. Ned was in the pilot house. He could see a clear field in front of him.