He snorted, folded up the little sheet and thrust it into his green silk tunic, as he sprang nimbly upon the moving sidewalk.

"What chance have I to see the Prince of Space?"

About him, the slender spires of widely spaced buildings rose two hundred stories into a blue sky free from dust or smoke. The white sun glinted upon thousands of darting heliocars, driven by silent electricity. He threw back his head, gazed longingly up at an amazing structure that rose beside him—at a building that was the architectural wonder of the twenty-second century.


Begun in 2125, Trainor's Tower had been finished hardly a year. A slender white finger of aluminum and steel alloy, it rose twelve thousand feet above the canyons of the metropolis. Architects had laughed, six years ago, when Dr. Trainor, who had been an obscure western college professor, had returned from a vacation trip to the moon and announced his plans for a tower high enough to carry an astronomical observatory giving mountain conditions. A building five times as high as any in existence! It was folly, they said. And certain skeptics inquired how an impecunious professor would get funds to put it up. The world had been mildly astonished when the work began. It was astounded when it was known that the slender tower had safely reached its full height of nearly two and a half miles. A beautiful thing it was, in its slim strength—girder-work of glistening white metal near the ground, and but a slender white cylinder for the upper thousands of feet of its amazing height.

The world developed a hungry curiosity about the persons who had the privilege of ascending in a swift elevator to the queer, many-storied cylindrical building atop the astounding tower. Bill had spent many hours in the little waiting room before the locked door of the elevator shaft—bribes to the guard had been a heavy drain upon a generous expense account. But not even bribery had won him into the sacred elevator.

He had given his paper something, however, of the persons who passed sometimes through the waiting room. There was Dr. Trainor, of course, a mild, bald man, with kindly blue eyes and a slow, patient smile. And Paula, his vivaciously beautiful daughter, a slim, small girl, with amazingly expressive eyes. She had been with her father on the voyage to the moon. Scores of others had passed through; they ranged from janitors and caretakers to some of the world's most distinguished astronomers and solar engineers—but they were uniformly reticent about what went on in Trainor's Tower.

And there was Mr. Cain—"The mysterious Mr. Cain," as Bill had termed him. He had seen him twice, a slender man, tall and wiry, lean of face, with dark, quizzical eyes. The reporter had been able to learn nothing about him—and what Bill could not unearth was a very deep secret. It seemed that sometimes Cain was about Trainor's Tower and that more often he was not. It was rumored that he had advanced funds for building it and for carrying on the astronomical research for which it was evidently intended.

Impelled by habit, Bill sprang off the moving walk as he glided past Trainor's Tower. He was standing, watching the impassive guard, when a man came past into the street. The man was Mr. Cain, with a slight smile upon the thin, dark face that was handsome in a stern, masculine sort of way. Bill started, pricked up his ears, so to speak, and resolved not to let this mysterious young man out of sight until he knew something about him.

To Bill's vast astonishment, Mr. Cain advanced toward him, with a quick, decisive step, and a speculative gleam lurking humorously in his dark eyes. He spoke without preamble.