Joe was already going up the ladder. He climbed to the steel steps of the tower leg and climbed those to the second landing, where Eberly had been standing a minute before. Because he was taller, he could hang on to the diagonal strut longer. The breeze was stronger at fifty feet than he’d expected. The steel ball slowly rolled, and although he knew he was being watched from below, he felt oddly alone with the bomb, as if it had been waiting only for him. He spread his arms wide, catching the wind, and walked with a quick, steady pace across the beam to the descending diagonal brace and the other tower leg.

The skate was jammed. He called down for a hammer and caught it as it spun up. When he hit the skate, it freed and the bomb gently swung to the center of the tower. He tucked the hammer into his belt and walked, arms out, back across the beam.

He was vaguely aware of someone saying “Bravo,” down on the ground. He continued up the tower steps, rising to the second and third landings and on to the platform at the top. Most of the platform was taken up by an eight-by-twelve shed of corrugated sheet iron. Outside was the engine and hoist. He started the engine. As the pulley wheel turned, the cable slipped back into its groove. He could see the bomb inching up the scaffolding again. He kept his heel on the engine switch, ready to stop it in case the skate jammed a second time.

West, he had a distant view of volcanic cones. South was more interesting. A smudge showed on the desert floor where a practice blast, a mere one hundred tons of TNT spiced with isotopes, had been set off on V-E Day. Firebreaks had been plowed around the blast, giving it the look of a bull’s-eye. Farther on was the ranch house where Harvey had assembled the core the day before. There were random scars of tire tracks and a blacktop road that ended in the middle distance at South-10,000, the control bunker six miles away that would fire the bomb. He could just make out the slap-up buildings and the windmill of the Base Camp ten miles off. Behind the camp was a dry sea of brush and dust that lapped against the Oscura Mountains. Oscuro meant “dark.” Low and broken, the Oscuras seemed to lie in the shadow of some larger, invisible mountains. It was a region of illusion. On the other side of the Oscuras were snowy dunes called White Sands. He noticed that blacktop roads also ran west and north from the tower, new roads virtually without traffic, in place purely for disaster.

“The fact is, I’m scared of heights.” Eberly had climbed back onto the platform.

“Heights are about the last thing you need to be afraid of around here,” Joe said.