Janus plainly showed his relief, as he winked at Mark, who said, "That was some chance you took. Suppose it hadn't worked?" "But it did work! That was the final test, and it was necessary. I had to know how it would react against the beams." Mark ventured a question. "Frequency Tuner? Is that what gave you the acceleration? I knew it wasn't rocket power!" Brownell turned piercing black eyes upon him. "Eh? Janus, who is this?" Janus vouched for Mark, explained his presence aboard. He added: "The Bureau's after an invention of his, too. A camera." The Professor was startled. "Did you say a camera? Since when do they--" "Ah, but Mark's is a very special camera." Janus smiled maddeningly, but in the next instant was clapping a friendly hand on Mark's shoulder. "Don't worry, Travers, your secret's safe with us. We don't ask questions. You've a right to know our destination, though; come on, I'll show you." They repaired to the chart room, where Janus indicated a moving red line on a glass-encased chart of the solar system. Other lines were being traced, too, at various angles to their trajectory. "The red line is our present trajectory. The others are the orbits of the planets. See, there's Jupiter behind us; notice how close we came." Mark nodded. Already in his mind's eye he was extending their present parabola. Distances between these outer planets were vast beyond imagining! Saturn was just in sight, but at their present speed they would probably cross its orbit far in advance of the planet. Then came Uranus, and next Neptune. The space between Neptune and Pluto was vaster than all. Mark felt just a little staggered. There was no known record of men having come this far! Not beyond Jupiter, in fact. He turned to Janus. "How far do we go?" "All the way." "Pluto?" "Beyond." Mark thought that over. "There's no planet in our system beyond Pluto!" "But there is. Planet X. An eccentricity in the orbit of Pluto indicates there must be a planet beyond. For years astronomers have known this, but no telescope has been able to pick it out." Mark grinned weakly. "So that's where we're headed. I guess you know it'd be awfully easy to overshoot a mark like that!" "Not with the Frequency Tuner. I understand very little of it, but the Professor assures me it's a directional finder as well as a power unit." "Sure, sure. And assuming we locate Planet X and manage to land--what do you expect to find there?" * * * * * Janus' eyes were flecked with dancing lights. "What do we hope to find? George Ketrik! And if you know the man at all, you know that means adventure and riches." Ketrik! Mark's mind went back. He began piecing together things he had heard, fragments and rumors. The man Ketrik and his amazing exploits had become almost a legend! "But I have heard," Mark voiced slowly, "that Ketrik died! Plunged into the sun while trying to negotiate a landing on Vulcan."