"Ed!" He gripped me. In the air over us the Turber Time-aero came sailing! It was solid--not traveling in Time--merely sailing here in Space. Two or three hundred feet above us, moving slowly north! We stared with sinking hearts. This was so wholly unexpected. The aero seemed descending, as though it might land on the roof. A moment; and then it flashed, faded into phantom. There was an instant when I thought it had gone through the roof. The wraith of it vanished. We stood stricken. Was Turber taking Nanette into some other Time-world? Abandoning his enterprise here? It did not seem likely when he was winning. Or was the aero going into Time to try to find our tower? Had Turber some inkling that Lea was bringing us a superweapon? Was he sending his aero to try and prevent that? If so, were he and Nanette in the aero? We had no way of knowing. "I think we should go on," Alan whispered at last. "Nanette may be in the city. If they'll accept us as Turberites--if we can only get to her--" We got through the gateway. A guard was there. He chanced to speak English. We flung back our cloaks. "Special business for Dr. Turber. Good news!" There seemed only one fellow here. Then off to one side we saw a dozen or more, seated on the roof in a glow of light, lolling about, smoking. The fellow passed us. We went on. * * * * * The Turber roof was dim with dotted lights. But it was all in operation. Groups of soldiers at intervals; occasionally a transport car passing along on its narrow rails. The fellow at the gate had waved vaguely toward this viaduct we now were traversing. We had followed his gesture. Our idea was to locate some Turber official whom we might fool--or force--into giving us information about Nanette. A low metal building showed ahead of us. It was small; it seemed perhaps of only one room. An isolated, dark spread of roof was around it. This viaduct we were on led to it. The little house had open windows, low to the floor, and there was a glow of light within. I whispered: "Some official may be on duty there. If we can rush him--make him tell us--" A kiosk leading down into the city showed a hundred feet or so beyond the little building. We left the viaduct. We crept forward over the dark open roof. We came to one of the open windows of the building. There must have been at that instant a dark figure lurking near us on the roof. Watching us. But we did not see it. The window stood with its sill at our knees. We dropped low, peered in. A single metal room with a glow of light. A metal table-block held a strange instrument of tubes and coils. Strange to me; but not to Alan. It was a Time-vision instrument! Its screen stood facing us; upon it was an image of our tower, a phantom speeding tower! A man sat with his back to us, hunched over the instrument. It was Turber! He was alone in the room. Alan's lips went to my ear: "I'll go first."