Ray got in the jeep. “Only eight hours to go to the fight. Turns out your old pal Hilario’s insisting on a minimum one-thousand-dollar bet from every spectator just to hold down the traffic. It’s a Texas crowd, Chief.”

“That’s good. It helps the odds. What are they now?”

“Holding at two to one. There’s a lot of confidence in the boy. I don’t like the crowd, Chief.”

“We’ll cover the bets. Don’t worry about the crowd, we have the MPs.”

Ray watched Oppy coming back through the brush. “I’m so nervous I could piss a marble.”

“That tent over the picnic tables where they had church this morning,” Joe said. “You think you can appropriate it for the fight?”

“Sure. Why?”

“It’s going to rain.”

As Oppy went by the tank it made a 90-degree turn, rolled over an ironwood tree and headed for him. Ray was gawking up at the sky. Joe was caught on the other side of the jeep. Oppy turned and watched in a defenseless stupor as the tank clattered, dipped, rose. Joe was prepared to save Oppy from nuclear mishap, not from a defanged albino Sherman tank. As it loomed over Oppy, it stopped. A hatch popped open and a head wearing a white cotton cap and goggles peered out.

“ ‘From this crude lab that spawned a dud,’ ” the tanker declaimed with a heavy Italian accent, “ ‘their necks to Truman’s axe uncurled. Lo, the embattled savants stood and fired the flop heard round the world.’ ”

The gloomy ditty was popular on the Hill. The tanker pulled off his goggles and cap to reveal cheerful eyes and dark receding hair. It was Fermi.

“Actually, I would estimate the chances of igniting the entire atmosphere at one in three thousand. Acceptable. The chances of incinerating New Mexico at thirty to one. The bomb will work.” He tapped his bald spot. “The problem is suntan lotion. Teller bought the last bottles so he wouldn’t burn from watching the blast. Edward really thinks the bomb will work.” Fermi pulled his goggles and cap down. “Now I play with my new toy.”

The hatch closed. As the tank rolled into reverse, Ray ran to catch up.

At four in the afternoon, four hours before the fight and ten hours before Trinity was scheduled, Oppy and Joe climbed the tower. The detonators were attached and the leads coiled around the gray sphere of the bomb to two detonator boxes. Extra wires, crates and pulley ropes crowded the shed. Joe slipped out to the platform. A pair of artillery spotter’s binoculars hung on the hoist, and he used them to scan the test site.

Oppy followed Joe out. “I feel as if we’re two men mounting the gallows together,” he said. “Everyone else is so confident. Did you see the standing orders for today? ‘Look for four-leaf clovers.’ ”