“Oh, Tom, what happened?” exclaimed Mary when she saw him in bed, all bandaged up. “That’s what I’d like to know,” he answered, with a smile. “It was like a premature Fourth of July celebration.” “Are you much hurt?” the girl faltered. “Nothing more than shock and scratches,” Tom answered. “I’ll be up and around in another day.” However, it was three days before Dr. Layton would allow Tom to get out of bed. Meanwhile nothing had been heard from Ned Newton. He had not gone to New York, that was evident, unless something had happened to him there, and he was not around Shopton, the town on Lake Carlopa where the Swifts’ large plant was located. “It’s mighty queer,” said the worried Mr. Newton, when Tom was forced to admit that his New York theory was useless. “Where could he be keeping himself?” “I can’t imagine,” Tom said. He was much broken up over the disappearance of his chum. He knew Ned well enough to know that he was not staying away from choice, though Tom did not communicate his suspicions to Mr. Newton. As soon as Tom was able, he went out to the laboratory. The scene of ruin on the lower floor was not so bad as he had feared, but the back and upper part of the laboratory was pretty well burned away. Then Tom had the improvised nailed-up door removed so he might enter the room where he had set up his talking-picture machine. “I hope it’s all right,” the young inventor murmured as he approached the apparatus. “They said it was, after the fire and explosion, but——” He gave a cry of dismay as he saw that, though the main part of the marvelous new machine was intact, the force of the explosion had wrecked the delicate mechanism that he depended on to prevent any but authorized owners of the apparatus from using it. Tom’s secret invention was badly damaged. In addition, all the new radio tubes, of a kind never before used, had been shattered by the blast. “This sure is tough luck!” murmured Tom Swift. “This knocks me out! The fire wasn’t so bad, but the explosion—whew! This certainly is tough! But I’ll work double time and soon have it in shape again, and better than ever. Luckily, I have duplicate parts of that secret check apparatus, and I can get new tubes, though it will take time.” “You’d better go slow, Tom,” advised his father, who had come into the partly wrecked private room with his son. “First thing you know, you’ll blow yourself to pieces with these experiments of yours.” “It was no experiment of mine, Dad, that caused the explosion here!” said Tom decidedly. “It wasn’t?” “No. All my wires were in good shape. It was some outside force that did the damage. I believe some one planted an infernal machine in here, Dad!” “You do, Tom? Whom do you suspect?” “I—I hardly know what to say,” was the slow answer. “But I have one man in mind. Where’s Clark?” he asked suddenly, naming a young workman who was much in Tom’s confidence.