“Mr. Bell is very persuasive. He still may convince Josephine to change her mind. Let us fill her tanks, spin her motor, and make it warm for her.” They exchanged glances. Celere said, “I don’t see Joe’s Mudd’s mechanicians hanging about this morning. They’ll be ready to go when the fog lifts. Shouldn’t we be? Just in case?”

That got them going. It was after all a race, and though they were better detectives than mechanicians, they had been competing daily for forty-eight days and four thousand miles.

“Start fueling. I will be right back.”

He went to the tiny stateroom they had given him on the train and returned carrying a yard-long, six-inch-wide corrugated paper tube sealed at either end and shoved it into the driving nacelle.

“What’s that?” asked a detective.

“San Francisco Inquirer flag, which Josephine is supposed to wave when she lands at the Presidio. What is wrong with motor?”

“What do you mean?”

“I do not like the sound.”

“Sounds fine to me.”

Celere looked the detective-mechanician in the eye. Then he flashed his most winning smile. “Let us make a deal, you and me, sir. I will not arrest criminals. You will not tell me that a flying-machine motor sounds like it will not suddenly stop in the sky.”

“Sorry, Celere. You’re right. What do you hear?”

“Bring me soapbox.” He climbed on the box and into the nacelle and played with the throttle, revving and slowing the Antoinette. He cocked his ear, shaking his head in puzzlement. “Pull chocks. Let’s taxi her around a little.”

“Careful you don’t run into anything. Can’t see fifty feet.”

The mechanicians pulled the wooden blocks that were holding the wheels in place.

Celere revved the motor. “You hear? You hear?”

“I’m not sure.”

“Listen . . . Here, I make go faster.”

He opened the throttle all the way. The Antoinette’s crisp burble increased to a roar. He turned the rudder, shaped the wings, raced fifty yards along the grass, and soared into the fog.

BELL ORDERED his Eagle made ready to fly, but there was no following Celere in the fog because no one knew which way he had gone. He had to wait until some railroad dispatcher wired a report that he had been spotted. Nearly an hour later, Isaac Bell received a telephone call from the railroad detectives Tom Griggs and Ed Bottomley.

“Are you sure you got Harry Frost?”

“I laid him personally on a slab of ice in the Fresno police station.”