They had but to look at each other to see that they were free. Nothing gripped their feet to hold them back. Of course the way was slippery, but no more so than an icy surface which one essays in ordinary shoes. What then caused their fear? * * * * * The plane, so plainly visible there ahead and above, was like a haven of refuge to them. They panted inside their helmets and their breath misted the glass of their masks. But they stumbled on, making the best speed they could under the circumstances. Perhaps if they took, off, and regained their courage, returned to normal in surroundings they knew and understood, they could come back and try again, after having heard each other's voices. The silence, the sign manual, the odd, awesome sensations, all combined to rob them of courage. They must get it back if they were to succeed. And they had been away from the plane for almost an hour. Hadley would be waiting for some news. The plane was twenty yards away--and almost at the same time Eyer and Jeter saw something queer about it. At first it was hard to say just what it was. They rushed on. They were within ten yards of the plane when a wail of anguish was born--and died--in two soundproof helmets. There was no questioning the fact that the plane had settled into the surface of the field. The plane was invisible below the tops of the landing wheels, as though the plane were sinking into invisibility, slowly dissolving from the bottom. "Understand?" Jeter's fingers almost shouted. "Understand why we felt the desire to keep moving? This field is alive, Eyer, and if we stand still it will swallow us just as it is swallowing our plane! Let's get in fast; maybe we can still pull free from the stuff and take off." They were racing against time and in the heart of each was the feeling that whatever they did, their efforts would be hopeless. Still, the spinning propeller of their plane gave them strength to hope. They went through the succession of doors as rapidly as they dared. Once in the comfort of their cabin they doffed their stratosphere suits with all possible speed. Jeter was the first free. He jumped to the controls and speeded up the motor. In a matter of seconds it was revving up to a speed which, had it been free, would have pulled the plane along at seven hundred miles an hour at the height at which they were. But the plane did not move! * * * * * Jeter slowed the motor, then started racing it fast, trying to jerk the fuselage free of the imbedded wheels, but they would not be released. Both men realized that the wheels had sunk from sight while they had been delayed coming through the succession of doors--that the plane had sunk until the invisible surface gripped the floor of the fuselage. Perspiration beaded the faces of both men. Eyer managed a ghastly grin. Jeter's brow was furrowed with frantic thought as he tried to imagine a way out.