the ovoid’s transparent walls. Mason’s eyes ached as he watched it.
Then it snapped out and vanished. It was gone.
Coldly Greddar Klon said, “It is ended. My experiment is finished—and successful.”
He touched the control board. “One test, though. We’ll move back in time—for one revolution of the Earth.”
The ship trembled, swayed. And suddenly utter, stygian blackness fell, through which screamed the vibration of energy inconceivable!
Chapter VI
Terror in Al Bekr
Before Mason could do more than catch his breath light came again. The ship had apparently not moved—yet the scene visible through the transparent walls was entirely different.
No longer were they in the room of the twin monoliths. The ship hung in empty air twenty feet above the roofs of a strange, archaic city. It was Al Bekr, Mason knew—but Al Bekr as it had been before the Master’s arrival.
A city of roughly-cut stone and mud-daubed huts, such a city as Babylon might have been before the days of its splendor—like Chaldean Ur before its ruin. Men and women moved quietly about the streets. They had not as yet glimpsed the ship hovering above.
“I am satisfied,” the Master said. “I can control the time-change accurately. Now we return.”
Again darkness. And again it lifted, to show the room of the green towers. Greddar Klon sent the ship drifting down to the distant floor.
“When are you going to start?” Mason asked. The cold eyes probed him.
“Tomorrow. You had best return to your apartment and rest. I will need your aid soon.”
Mason turned to the opening port. He vaulted lightly down and went to a tunnel-mouth. But something he had read in the Master’s glance made him wary. He lurked in the passage out of sight, waiting.
Nor had he long to wait. Presently a low, distant voice sounded.
“You sent for me, Greddar Klon.”
The voice of Nirvor, the Silver Priestess.
And the Master’s reply:
“All is ready. We can start now.”
A pause. Then Nirvor said, “My leopards. I must get them.”
Mason wiped his forehead. So Greddar Klon intended betrayal. He planned to return to the future with Nirvor, leaving Mason behind. Well—Mason would not have gone without Alasa; but the thought came to him: would it not be best thus? With Nirvor and Greddar Klon gone, Alasa could rule Al Bekr as before.
And then—what? Mason himself would be marooned in a long-forgotten time-sector, together with Murdach, the man from the future. Perhaps Murdach could help. True, Mason had been ordered to obey the Master till he received word from the Sumerian, but this was an emergency.
If he could only find Erech! But he did not know where to look. Mason, about to turn away, was halted by Nirvor’s return. He edged forward cautiously, listening to the priestess’ soft laughter, and caught sight of the woman. She was moving toward the time-ship, the two leopards beside her. She entered it. The leopards sprang lithely through the portal. Greddar Klon followed.
What now? Indecision held Mason motionless. His impulse was to halt the Master, kill him if possible. But how? The atomic shield could not be penetrated by any weapon made by man. And there were the leopards—
The problem was solved for him. The ship suddenly grew hazy, a shimmering, oval shadow. It faded and was gone.
Where the time-ship had been was nothing. It had been launched on its incredible journey into the future.
A hand gripped Mason’s shoulder. He whirled to face Erech.
“Murdach sent me,” the Sumerian said. “The Master’s gone, eh?”
Mason nodded wordlessly. Suddenly Erech grinned.
“Good! That’s what Murdach wanted. He sent me to watch you, to stop you from doing anything rash. There was no time before to warn you. Come along now. I’ve freed Murdach, with the aid of his magic weapon. He’s with Alasa.”
Mason was conscious of a heightening of his pulses as he followed the Sumerian along the corridor. The robots were not visible; Mason