Admiral Walter had paled slightly under his deep tan. In stunned silence, the Navy officers and scientists watched as Tom's lean hands manipulated two controls. "What are those for?" Bud asked. "One's to speed up our recovery missile," Tom explained. "Looks like a slim hope, though, from the way that third blip is homing on target. This other control has just caused every instrument on this ship, and all the others in the task force, to make permanent records on magnetic tape of all their readings. "If a collision occurs and the probe missile falls into the sea," Tom went on, "there's only one hope of recovery--to plot the exact geographical position and then get to the spot before the enemy does!" "Roger!" Bud agreed. It was obvious that Tom's fears about the missiles colliding were well founded. The mystery blip had veered as the recovery missile speeded up. Within seconds, the three blips met on the screen and fused into a single spot of light. "The probe missile's no longer responding to control!" one of the telemetering scientists called out. Admiral Walter, grim-faced, flashed a questioning look at Tom. "Then recovery has failed?" "I'm afraid so, sir." The fused blip was still visible on screen as the radar dishes tracked it, moving in a way that indicated a steep downward plunge. For a moment Tom felt numb with despair. But he set his jaw firmly and turned to the admiral. "Sir, I'd like helicopters readied for take-off immediately," Tom said. "As soon as the tracking instruments lose contact, have the recording tapes picked up from every ship in the task force and brought here to the _Recoverer_." Admiral Walter nodded tersely. "Very well. Then what?" "I'll get to work right now," Tom replied, "and lay out a computer program to process the readings." The data--consisting of millions of information "bits" from the shipboard instrument tapes--would be fed to an electronic brain. The brain would then calculate the probable location in latitude and longitude of the sunken missile. As the admiral snapped out orders, Tom exchanged a brief worried glance with his father. Each was pondering the same thought. _Could Tom find the lost Jupiter probe missile? Or would their enemy locate it first?_ CHAPTER II UNDERSEA SURVEY With an effort, Tom forced all thoughts of failure out of his mind and concentrated on the job at hand. In an hour he had the computer program blocked out. Mr. Swift and several of the other scientists checked his work. Each nodded approval. By this time, the fused blip had long since disappeared from the radarscopes, indicating that the Jupiter probe missile--or what was left of it--had plunged to the ocean bottom. "What's your next move, Tom?" Admiral Walter asked. "No point in wasting time waiting for the computer results," Tom decided. "Suppose Bud and I fly back to Swift Enterprises and organize a search party."