Tom, we're having a problem with the gyro-stabilizer, said Mark Faber, gray-haired president of the Faber Electronics Company. "Hope you can find out what's wrong." The eighteen-year-old inventor accepted the challenge with a smile. "I'll be glad to try, sir," he replied. Bud Barclay, a dark-haired young flier and Tom Swift Jr.'s closest friend, chuckled. "If anyone can get the bugs out of your new invention, genius boy here will do it!" The two boys followed Mr. Faber and his engineers to a wooden building which was tightly guarded. Inside, a secret rocket-telemetering device was mounted on its test stand. "As you know, Tom," Mr. Faber began, "the usual conditions of rocket flight will be -" He broke off with a gasp of astonishment as the whole building suddenly began to shake.