He drew back, staring, straining every nerve to think.... And somehow his eyes were drawn to the back of the laboratory and he saw Smithers teetering on his feet, with his hands clasped queerly to his body, and a strange man standing in the door of the laboratory with an automatic pistol in his hand. The automatic had a silencer on it, and its clicking had been drowned out, anyhow, by the roaring of the crude-oil engine. The man was small and dark and natty. His lips were drawn back in a peculiar mirthless grin as Smithers teetered stupidly back and forth and then fell.... The explosion of Tommy's own revolver astounded him as much as it did Jacaro's gunman. He did not ever remember drawing it or aiming. The natty little gunman was blotted out by a spouting mass of white smoke--and suddenly Tommy knew what it was that Denham wanted him to do. * * * * * There was rope in a loose and untidy coil beneath a work bench. Tommy sprang to it in a queer, nightmarish activity. He knew what was happening, of course. Von Holtz had seen the magnetic catapult at work. That couldn't be destroyed or its workings hidden like the ring catapult of Denham's design. He'd gone out to call in Jacaro's men. And they'd shot down Smithers as a cold-blooded preliminary to the seizure of the instrument Jacaro wanted. It was necessary to defend the laboratory. But Tommy could not spare the time. That white mist was moving upon Evelyn and her father, in that other world. It was death, as the terror of the wild things demonstrated. They had to be helped.... He knotted the rope to the end of the cord that vanished curiously somewhere among the useless mass of rings. He tugged at the cord--and it was tugged in return. Denham, in another world, had felt his signal and had replied to it.... A window smashed suddenly and a bullet missed Tommy's neck by inches. He fired at that window, and absorbedly guided the knot of the rope past its vanishing point. The knot ceased to exist and the rope crept onward--and suddenly moved more and more swiftly to a place where abruptly it was not. For the length of half an inch, the rope hurt the eyes that looked at it. Beyond that it was not possible to see it at all. Tommy leaped up. He plunged ahead of two separate spurts of shots from two separate windows. The shots pierced the place where he had been. He was racing for the crude-oil engine. There was a chain wound upon a drum, there, and a clutch attached the drum to the engine. He stopped and seized the repeating shotgun Smithers had brought as his own weapon against Jacaro's gangsters. He sent four loads of buckshot at the windows of the laboratory. A man yelled. And Tommy had dropped the gun to knot the rope to the chain, desperately, fiercely, in a terrible haste. * * * * * The chain began to pay out to that peculiar vanishing point which was here an entry-way to another world--perhaps another universe.