Russ waited for that attempt. There was nothing that could be done about it. The engines were developing every watt of power that could be urged out of them. If Craven had the power to break away, he would break away ... that was all there would be to it. An hour passed and the needle crept up a fraction of a point. Russ was still watching the dial, his mind foggy with concentration. * * * * * Suddenly the _Invincible_ shuddered and seemed to totter in space, as if something, some mighty force, had struck the ship a terrific blow. The needle swung swiftly backward, reached one mile a second, dipped to half a mile. Russ sat bolt upright, holding his breath, his teeth clenched with death grip upon the pipe-stem. Craven had blasted with everything he had! He had used every last trickle of power in the accumulators ... all the power he had been storing up. Russ leaped from the chair and raced to the periscopic mirror. Stooping, he stared into it. Far back in space, like a silver bauble, swung Craven's ship. It swung back and forth in space, like a mighty, cosmic pendulum. Breathlessly he watched. The ship was still in the grip of the space field! "Greg," he shouted, "we've got him!" He raced back to the control panel, snapped a glance at the speed dial. The needle was rising rapidly now, a full mile a second. Within another fifteen minutes, it had climbed to a mile and a half. The _Invincible_ was starting to go places! The engines still howled, straining, shrieking, roaring their defiance. In an hour the needle indicated the speed of four miles a second. Two hours later it was ten and rising visibly as Jupiter fell far behind and the Sun became little more than a glowing cinder. Russ swung the controls to provide side acceleration and the two ships swung far to the rear of Neptune. They would pass that massive planet at the safe distance of a full hundred million miles. "He won't even make a pass at it," said Greg. "He knows he's licked." "Probably trying to store some more power," suggested Russ. "Sweet chance he has to do that," declared Greg. "Look at that needle walk, will you? We'll hit the speed of light in a few more hours and after that he may just as well shut off his lens. There just won't be any radiation for him to catch." Craven didn't make a try at Neptune. The planet was far away when they intersected its orbit ... furthermore, a wall of darkness had closed in about the ships. They were going three times as fast as light and the speed was still accelerating! Hour after hour, day after day, the _Invincible_ and its trailing captive sped doggedly outward into space. Out into the absolute wastes of interstellar space, where the stars were flecks of light, like tiny eyes watching from very far away. * * * * *