The lodge’s walls and columns had the honeyed glow of varnished ponderosa pine. In keeping with the Christmas theme, red and green crepe festooned wagon-wheel candelabras and the open balconies of the second floor. Paper reindeer were pinned to the Navajo rugs on the walls. Atop the eight-foot-high stone mantel of the fireplace a cardboard St. Nick stood between Indian pots.

“Everyone’s here.” Foote leaned on the piano. He was a horsey Englishman in a threadbare tuxedo.

“Not everyone,” Joe answered while he played.

“You say. Who’s not here?”

“Soldiers aren’t here, MPs aren’t here, WACs aren’t here, machinists aren’t here, Indians aren’t here.”

“Of course not, we don’t want them here. It’s not their bloody bomb. Bad enough that we have the military command. Especially Captain Augustino creeping around like a Grand Inquisitor.”

“I’m ready.” Harvey Pillsbury brought Joe a bourbon. In his other hand he carried a clarinet. “I really appreciate this second chance, Joe.”

“Just blow. Last time you were so silent it was like playing with a snowman.”

Harvey had the contours of a snowman, fair downy hair and the high, nasal accent of West Texas.

“Be prepared for quantum improvement.”

“Whatever that means.” Joe finished the drink in a swallow.

He played “Machine Gun Butch” and everyone sang along. “ ‘… was a rough and ready Yankee, / He’ll never let the old flag touch the ground. / And he always will remember the seventh of December, / With his rat-tat-tat-tat-tat-tat, and he’ll mow them down.’ ” The English and Italians sang loudest, and the odd thing was that Joe liked them all, Foote included and Harvey especially. Most were Americans, the majority babies straight from college. The boys had loose ties and sweaty faces; the girls had short skirts and scrolls of hair around broad, polished foreheads. A rent party in Harlem it wasn’t, but they were trying.

Harvey had stood through “A String of Pearls,” clarinet raised and trembling and utterly mute. During “Don’t Sit Under the Apple Tree,” he licked the reed, forced a squeak, two notes in a row, then three. Halfway into “This Joint Is Jumpin’,” Joe switched to a bass stride, forcing Harvey to blow erratically through a riff like a butterfly flying for its life; at the end he beamed, red-cheeked and triumphant.

“ ‘White Christmas’?” he suggested.

Joe groaned. “A little knowledge is a gruesome thing.”

There was a stir across the room as Oppy and Kitty arrived. Better than a stir: veneration. The director of the Los Alamos Project was a spindly six feet tall with a close-cropped skull and beak of a nose that emphasized tapered eyes of startling blue. Younger physicists followed him, copying the hunch of his shoulders, his air of distraction. Kitty Oppenheimer had a flat, pretty face, a frowsy dress and dark, thick hair. Her friends were European wives, who surrounded her like bodyguards.