Santa Fe passed as an electric glow under an ashcolored sky. An Army hospital was pumping money into the town. Signs offered drinks, boots, curios.

As Oppy and Groves droned on about problems of the isolation of isotopes and allotropic states of plutonium, Joe wondered why he had gone to bed with Mrs. Augustino. Was it her he wanted? Some other woman? Any woman?

Like a conscience a state trooper’s motorcycle emerged, siren wailing, from behind a sign that said, WAR BONDS ARE BULLETS!

The general’s travels were secret; it was understood he didn’t want to talk to any local justice of the peace. Joe floored the accelerator. New Mexico troopers had black uniforms and black cycles. At 100 mph, the dark silhouette became a dot in the rearview mirror. Swaying on passenger straps, Groves and Oppy went on talking about construction schedules. Fuchs spoke only when asked.

In the fields the breeze rattled rows of chili, unpicked because a farmer could walk into Boeing’s Albuquerque office, keep going straight to Seattle to build B-29s and draw more money in a month than he’d ever seen in a year.

“Explode. Implode. Two apparently contradictory events at the same moment,” Oppy was saying. “I wouldn’t suggest trying to explain it to the President. Still, it’s a sweet concept.”

Past Albuquerque and through the lower valley, crossing the Rio so often it seemed a dozen rivers, Oppy and Groves discussed problems ranging from plutonium assembly to sugar for the commissary. The car pressed against a headwind toward dull clouds that built and receded at the same time. At Antonio, a farm town of dimly lit windows, they left the highway for an eastbound single lane of frayed macadam, crossed the Rio one last time and entered a vast, tilted basin of scrub and low cactus. Here the clouds moved forward and snow began to fall, lightly to begin with, tracing the wind, more heavily as the sun was covered, packing on the wipers and coating the headlights.

“If Hitler has the bomb …” Groves was saying. “We get reports that this winter offensive of the Germans is just to stall while he finishes some secret weapon. Suddenly he has jet-propelled planes, new rockets.”

“If Hitler has the device, he’ll use it on the Russians,” Oppy said.

“Is that a bad idea?” Groves asked.