He had an astonishing gift for accents, and he mimicked, faultlessly, an English aristocratic drawl. “‘The Japanese,’ this Englishman proclaimed to all in the smoking room, ‘display a natural aptitude for espionage, and a cunning and self-control not found in the West.’”

Yamamoto laughed. “That sounds like Commander Abbington-Westlake of the Admiralty’s Naval Intelligence Department, Foreign Division, who was spotted last summer painting a watercolor of the Long Island Sound that just happened to contain America’s latest Viper Class submarine. Do you suppose the windbag meant it as a compliment?”

“The French Navy he penetrated so successfully last month would hardly call Abbington-Westlake a windbag. Did you keep the money?”

“I beg your pardon?”

“The money you were supposed to put in Arthur Langner’s desk. Did you keep it for yourself?”

The Jap stiffened. “Of course not. I put it in his desk.”

“The Navy’s enemies in Congress must believe that their star designer, their so-called Gunner, was guilty of taking a bribe. That money was vital to our message to the Congress to make them wonder what else is rotten in the Navy. Did you keep the money?”

“I should not be surprised that you would ask such a degrading question of a loyal associate. With the heart of a thief you assume that everyone is a thief.”

“Did you keep the money?” the spy repeated. A physical habit of maintaining utter stillness masked the steely power of his compact frame.

“For the last time, I did not keep the money. Would you feel more secure if I swore on the memory of my old friend-your father?”

“Do it!”

Yamamoto looked him full in the face with undisguised hatred. “I swear on the memory of my old friend, your father.”

“I think I believe you.”

“Your father was a patriot,” Yamamoto replied coldly. “You are a mercenary.”

“You’re on my payroll,” came the even colder retort. “And when you report to your government the valuable information you picked up in the Washington Navy Yard’s Gun Factory-while working for me-your government will pay you again.”

“I do not spy for the money. I spy for the Empire of Japan.”

“And for me.”

“GOOD SUNDAY MORNING TO all who prefer their music minus the sermon,” Arthur Langner greeted his friends at the Gun Factory.

Rumpled in a baggy sack suit, his thick hair tousled and bright eyes inquisitive, the Naval Ordnance Bureau’s star designer grinned like a man who found interest in all he saw and liked the strange bits most of all. The Gunner was a vegetarian, an outspoken agnostic, and devoted to the theories of the unconscious mind put forth by the Viennese neurologist Sigmund Freud.

He held patents for an invention he named the Electrical Vacuum Cleaning Machine, having hitched his fertile imagination to a heartfelt notion that science-based domestic engineering could free women from the isolation of housework. He also believed that women should have the right to vote, work outside the home, and even practice birth control. Gossips smirked that his beautiful daughter, who ran with the fast set in Washington and New York, would be a prime beneficiary.

“A one-man lunatic fringe,” complained the commandant of the navy yard.

But the chief of Naval Ordnance, having observed Langner’s latest 12-inch/.50 caliber gun shoot up his Sandy Hook Atlantic Test Range, retorted, “Thank God he works for us instead of the enemy.”

His Sunday-morning chamber musicians, a ragtag mix of Gun Factory employees, laughed appreciatively when Langner joked, “Just to assure any eavesdropping blue noses that we’re not complete heathens, let’s start with ‘Amazing Grace.’ In G.”

He sat at his grand piano.

“May we please have an A first, sir?” asked the cellist, an expert in armor-piercing warheads.

Langner lightly tapped middle A, to which note the strings could tune their instruments. He rolled his eyes in mock impatience as they fiddled with their tuning pegs. “Are you gentlemen cooking up one of those new atonal scales?”

“One more A, if you can spare it, Arthur. A little louder?”

Langner tapped middle A harder, again and again. At last the strings were satisfied.

The cellist began the opening notes of “Amazing Grace.”

At the tenth measure, the violins-a torpedo-propulsion man and a burly steamfitter-took up “once was lost.” They played through and began to repeat.

Langner raised his big hands over the keys, stepped on the sustain pedal, and lofted “a wretch like me” on a soaring G chord.

Inside the piano, Yamamoto Kenta’s paste of nitrogen iodide had hardened to a volatile dry crust. When Langner fingered the keys, felt hammers descended on G, B, and D strings, causing them to vibrate. Up and down the scale, six more octaves of G, B, and D strings vibrated sympathetically, jolting the nitrogen iodide.

It exploded with a sharp crack that sent a purple cloud pouring from the case and detonated the sack of Cordite. The Cordite blew the piano into a thousand slivers of wood and wire and ivory that riddled Arthur Langner’s head and chest, killing him instantly.

BY 1908, THE VAN DORN DETECTIVE AGENCY MAINTAINED a presence in all American cities of consequence, and its offices reflected the nature of each locality. Headquarters in Chicago had a suite in the palatial Palmer House. Dusty Ogden, Utah, a railroad junction, was served by a rented room decorated with wanted posters. New York’s offices were in the sumptuous Knickerbocker Hotel on 42nd Street. And in Washington, D.C., with its valuable proximity to the Department of Justice-a prime source of business-Van Dorn detectives operated from the second floor of the capital city’s finest hotel, the new Willard on Pennsylvania Avenue, two blocks from the White House.

Joseph Van Dorn himself kept an office there, a walnut-paneled den bristling with up-to-date devices for riding herd on the transcontinental outfit he commanded. In addition to the agency’s private telegraph, he had three candlestick telephones capable of long-distance connections as far west as Chicago, a DeVeau Dictaphone, a self-winding stock ticker, and an electric Kellogg Intercommunicating Telephone. A spy hole let him size up clients and informants in the reception room. Corner windows overlooked the Willard’s front and side entrances.

From those windows, a week after Arthur Langner’s tragic death at the Naval Gun Factory, Van Dorn watched apprehensively as two women stepped down from a streetcar, hurried across the bustling sidewalk, and disappeared inside the hotel.

The intercommunicating phone rang.

“Miss Langner is here,” reported the Willard’s house detective, a Van Dorn employee.

“So I see.” He was not looking forward to this visit.

The founder of the Van Dorn Detective Agency was a heavily built, bald-headed man in his forties. He had a strong Roman nose, framed by bristling red whiskers, and the affable manner of a lawyer or a businessman who had earned his fortune early and enjoyed it. Hooded eyes masked a ferocious intelligence; the nation’s penitentiaries held many criminals gulled into letting the big gent close enough to clamp on the handcuffs.

Downstairs, the two women riveted male attention as they glided through the Willard’s gilt-and-marble lobby. The younger, a petite girl of eighteen or nineteen, was a stylishly dressed redhead with a vivacious gleam in her eyes. Her companion was a tall, raven-haired beauty, somber in the dark cloth of mourning, her hat adorned with the feathers of black terns, her face partially veiled. The redhead was clutching her elbow as if to give her courage.

Once across the lobby, however, Dorothy Langner took charge, urging her companion to sit on a plush couch at the foot of the stairs.