The spider-vehicle lurched and swayed, even its marvelous system of shock-absorbers protesting as it climbed steeply, straddling upward from rock to rock. Dworn clutched at handholds inside the pitching cabin and tried to combat the sympathetic lurching of his stomach. Qanya huddled tensely over the controls, slim hands flashing nimbly to and fro as with incredible deftness she guided the laboring machine. Dworn risked a glimpse from the turret-windows, then shut his eyes with a rush of giddiness. They were climbing now up the steepest part of the great slide, where the mountainside had collapsed in a chaos of splintered rock and tumbled crags that would have been utterly impassible for any wheeled vehicle. Below them, the sloping valley floor they had left appeared from this height entirely flat and sickeningly far away. And still the cliff-heads frowning above them seemed terribly remote. "How ... far?" gasped Dworn. "It can't be very far now to the top," said Qanya, without glancing up from her absorbed concentration. Both their lives were in her hands; a slip, a misstep, and they might fall hundreds of feet among the jagged rocks to their death. For seconds at a time, the walking machine poised motionless, one or more of its clawed limbs groping for footholds. As it clambered painfully upward, it was hopelessly exposed to attack if it should be sighted from the air. _Dworn_, the beetle told himself savagely, _you are not only a ghost, you are an insane ghost_. _Only a madman would have undertaken such a journey._ The cabin heeled wildly as the machine grappled a ledge and, its engine panting at full throttle, levered itself upward a few more feet. He had commanded the spider girl to find the route by which her people had descended. But twice already they had missed the way and had arrived at dead ends beyond which it was impossible to climb higher; twice they had been forced to descend and search for an easier path. It had been scarcely noon when they started; now the sun was already sinking low. Dworn could not even be sure that he would find his sworn enemies beyond the Barrier. But the duty of vengeance was all he had left to live for, since what was to have been his triumphal return had ended in bereavement and catastrophe. _And a dead man_, thought Dworn bleakly, _needs something to live for, even more than other people do_. The world came level again, for the moment. The machine sidled precariously along a narrow ledge girdling an unscalable wall of rock, as Qanya sought a spot to resume the ascent. Dworn winced at the thought that the way might be blocked again. But, no--fifty yards further on, the wall was breached, and toppled boulders formed a perilous but not impossible stairway.