Celere was fully aware that his was not a new idea. Visionary artists and cold-blooded soldiers had long imagined speedy airships capable of carrying many passengers, or many bombs. But other men’s ideas were his lifeblood. He was a sponge, as Danielle Di Vecchio had screamed at him. A thief and a sponge.

So what if Dmitri Platov, the fictional Russian aeroplane mechanician, machinist, and thermo engine designer, was his only original invention? An Italian proverb said it all: Necessity is the mother of invention. Marco Celere needed to destroy his competitors’ flying machines to guarantee that Josephine won the race with his machine. Who better to sabotage them than helpful, kindly “Platov”?

Celere was truly an expert toolmaker, with a peculiar talent for picturing the finished product at the outset. The gift had set him above common machinists and mechanicians when he apprenticed at age twelve in a Birmingham machine shop—a position that his father, an immigrant restaurant waiter, had procured by seducing the owner’s wife. When metal stock was put on a lathe to be turned into parts, the other boys saw a solid block of metal. But Marco could visualize the finished part even before the stock started spinning. It was as if he could see what waited inside. Releasing the part waiting inside was a simple matter of chiseling away the excess.

It worked in life, too. He had seen inside Di Vecchio’s first monoplane a vision of Marco Celere himself winning contracts to build warplanes to defeat Italy’s archenemy, Turkey, and seize the Turkish Ottoman Empire’s colonies in North Africa.

Soon after the machine he copied had smashed, he saw vindication “waiting inside” a luxurious special train that rolled into San Francisco’s First California Aerial Meet. Off stepped Harry Frost and his child bride. The fabulously wealthy couple—the heavy bomber and the nimble escort—richer by far than the King of Italy—had given him a second chance to sell futuritial war machines.

Josephine, desperate to fly aeroplanes and starved for affection, was seduced without difficulty. Remarkably observant, decisive, and brave in the air, she was easily led down on earth, where decisiveness turned impulsive, and where she seemed curiously unable to predict the consequences of her actions.

Along had come the Whiteway Cup Cross-Country Air Race to prove his aeroplanes were the best. They had to be. He had copied only the best. He had no doubt that Josephine would win with her flying skill and with him sabotaging the competition. Winning would vindicate him in the eyes of the Italian Army. Past smashes would be forgotten when his warplanes vanquished Turkey, and Italy took Turkey’s colonies in North Africa.

Two yellow specks appeared in the distance: Josephine, with Isaac Bell right behind and above, following like a shepherd. The crowd began cheering “Josephine! Josephine!” Whiteway was a genius, Celere thought. They truly loved their Sweetheart of the Air. When she won the cup, everyone in the world would know her name. And every general in the world would know whose flying machine had carried her to victory.

If Steve Stevens managed to finish, all the better—Celere would sell the Army heavy bombers as well as nimble escorts. But that was a very big if. Uncontrollable vibration, due to a failure to synchronize the twin engines, was shaking it to pieces. If Stevens smashed before he finished, Celere could blame it on the farmer’s weight and poor flying. He had to admit that, by now, young Igor Sikorsky would have solved the vibration problem, but it was beyond Celere’s talents. And it was too late in the game to steal those ideas even if Sikorsky were here instead of in Russia. If only the thermo engine he had bought in Paris had worked out, but that, too, had been beyond his talents.

Now they lay unconscious at Harry Frost’s feet, surprised by hammer blows of his fists after he sprang not from the stairs’ penthouse but from the elevator’s, where he had hidden since dawn.

Frost steadied a Marlin rifle on a square stone between two notches in the parapet and waited patiently for Josephine’s head to completely fill the circle of his telescopic sight. She was coming straight at him, preparing to circle the armory as required by the rules, and he could see her through the blur of her propeller. This might not be as satisfying a kill as strangling her, but the Van Dorns had left him no opportunity to get close. And there were times a man did best to take what he could get. Besides, the telescope made it seem as if they were facing each other across the dinner table.

Driving with his right hand, he swiveled his Remington autoload rifle with his left. He saw a startled expression on Josephine’s face as he hurtled past her. Ahead, among the stone notches, he saw the sun glint on steel. Behind the flash, half hidden in shadow, the bulky silhouette of Harry Frost was drawing a bead on Josephine’s yellow machine.

Then Frost saw the American Eagle plummeting toward him.

He swung his barrel in Bell’s direction and opened fire. Braced on the solid roof of the armory, he was even more accurate than he had been from the oyster boat. Two slugs stitched through the fuselage directly behind the controls, and Bell knew that only the extraordinary speed of his dive had saved him when Frost underestimated how swiftly he would pass.

Now it was his turn. Waiting until his spinning propeller was clear of the field of fire, the tall detective triggered his Remington. Stone chips flew in Frost’s face, and he dropped his rifle and fell backwards.

Isaac Bell turned the Eagle sharply—too sharply—felt it start to spin, corrected before he lost control, and swept back at the armory. Frost was scrambling across the roof, leaping over the bodies of two fallen detectives. He had left his rifle where he had dropped it and was holding a hand to his eye. Bell fired twice. One shot shattered glass in the structure that housed the elevator machinery. The other nicked the heel of Frost’s boot. The impact of the powerful centerfire .35 caliber slug knocked the big man off his feet.

Bell wrenched the Eagle around again, ignoring the protesting shriek of wind in the stays and an ominous grinding sound that vibrated through the controls, and raced back at the red brick building to finish him off. Across the roof, the door of the stair house flew open. Soldiers with long, clumsy rifles tumbled through it and fanned out, forcing Bell to hold his fire to avoid hitting them. Frost ducked behind the elevator house. As Bell roared past, he saw the killer open a door and slip inside.

He looked down at the avenue in front of the building, saw that Josephine had alighted and that there was space for him. Down he went, blipping his motor. He hit the cobblestones hard, spun half around, recovered, and, when the tail skid had slowed him nearly to a stop, jumped down and ran up the front steps of the armory, drawing his pistol.

An honor guard of soldiers in dress uniforms holding rifles at port arms blocked his way.

“Van Dorn!” Bell addressed their sergeant, a decorated man of action whose chestful of battle ribbons included the blue-and-yellow Spanish-American War Marine Corps Spanish Campaign Service Medal. “There’s a murderer in the elevator house. Follow me!”

The old veteran sprang into action, running after the tall detective and calling upon his men. The inside of the armory was an enormous cathedral-like drill space as wide as the building and half as deep. The coffered ceiling rose as high as the roof. Bell raced to the elevator and stair shafts. The elevator doors were closed, and the brass arrow that indicated its location showed that the car was at the top of the shaft.

“Two men here!” he ordered. “Don’t let him out if the car descends. The rest, follow me.”

He bounded up four flights of stairs, with the soldiers clattering behind, reached the roof, and stepped outside just as Joe Mudd’s red Liberator roared around the building, yards ahead of Sir Eddison-Sydney-Martin’s blue Curtiss Pusher.

Bell ran to the elevator house. The door was locked.

“Shoot it open.”

The soldiers looked to their sergeant.

“Do it!” he ordered. Six men pumped three rounds of rifle fire into the door, bursting it open. Bell bounded in first, pistol in hand. The machine room was empty. He looked through the steel grate floor. He could see into the open, unroofed car, which was still at the top of the shaft immediately under him. It, too, was empty. Harry Frost had disappeared.

“Where is he?” shouted the sergeant. “I don’t see anyone. Are you sure you saw him in here?”

Isaac Bell pointed at an open trapdoor in the floor of the car.

“He lowered himself down the traction rope.”

“Impossible. There’s no way a man could hold on to that greasy cable.”

Bell dropped into the elevator car and looked down through the trap. His sharp eyes spotted twin grooves in the grease that thickly coated the braided steel wire that formed the traction rope. He showed the sergeant.

“Where the heck did he get a cable brake?”

“He came prepared,” said Bell, climbing up the side of the car to run for the stairs.

“Any idea who he was?”

“Harry Frost.”

Fear flickered across the old soldier’s face. “We were chasing Harry Frost?”

“Don’t worry. He won’t get far.”

“Chicago’s his town, mister.”

“It’s our town, too, and Van Dorns never give up.”