They went into the end of the factory that was less ruined than the central part, where the tank had crashed through, and made their way into what had been the office--the place where they had found the burned scraps of paper. "Hark!" exclaimed Ned, as they climbed up the broken steps. "I heard a noise." "It's him yellin'--like he did afore he threw out the note," said the boy. Then, as they listened, they heard a distant voice calling: "Hello! Hello, there! If that is any friend of mine, let me out, or send word to Mr. Damon or Ned Newton! Hello!" "Hello yourself, Tom Swift!" yelled Ned, too delighted to wait for any other confirmation that it was his friend who was shouting. "We've come to rescue you, Tom!" There was a moment of silence, and then a voice asked: "Who is there?" "Ned Newton, Mr. Damon, and some other friends of yours!" answered the young bank clerk, for surely the farmer and his son could be called Tom's friends. An indistinguishable answer came back, and then Ned cried: "Where are you, Tom? Tell us, so we can get you out!" They all listened, and faintly heard: "I'm in some sort of an old vault, partly underground. It's below what used to be the office. There's a flight of steps, but be careful, as they're rotten." Eagerly they looked around Mr. Damon saw a door in one corner of the office, and tried to open it. It was locked, but a few blows from the sledge smashed it, and then some steps were revealed. Down these, using due caution, went Ned and the others, and at the bottom they came upon another door. This was of sheet iron and was fastened on the outside by a big padlock. "Stand back!" cried Ned, as he swung the sledge, and with a few blows broke the lock to pieces. Then they pulled open the door, and into the light staggered Tom Swift, a most woe-begone figure, and showing the effects of his imprisonment. But he was safe and unharmed, though much disheveled from his attempts to escape. "Thank Heaven, you've come!" he murmured, as he clasped Ned's hand. "Is the tank all right?" "All right!" cried Ned. "And now tell us about yourself. How in the world did you get here?" "It's quite a yarn," answered Tom. "I've got to pull myself together before I answer," and he sank wearily down on a step, looking very haggard and worn. Chapter XXIII Gone "Here, eat some of this," and Ned held something out to his chum. "It'll bring you up quicker than anything else, except a cup of hot tea, and we'll get that as soon as you can get away from here," went on the young bank clerk. "What is it?" Tom asked, and his voice was very weary.