Bell heard shouts of alarm. Traffic came to a standstill. People reached under the wagon and helped him to his feet. He looked around confusedly, retrieving his hat and assuring passersby that he was not injured. He could see neither the shadow nor the backup operator waiting to trip him. But Detective Joel Wallace’s broad back was disappearing into a lane on the far side of Whitechapel, hot on the trail.

Isaac Bell chased after Joel Wallace, who was following the man in the bowler hat. The operator in tweed had peeled away early on, scurrying up Bishopsgate without looking back. The Van Dorn stayed with his boss as the man negotiated the ill-clad crowds on greasy cobblestone streets littered with scrap paper and horse manure. Bell caught up when Wallace stopped behind a cart with a broken wheel that was blocking the sidewalk.

“Heck of an acrobat,” Wallace said over his shoulder, his eyes fixed on an alley. “For a moment there, I thought he really got you.”

“Ran off with the circus once— Where’d he go?”

“Ducked into that beer house. We’re looking at the back door. Ought to be out any sec.”

The drizzle changed abruptly to cold rain that poured down from the dark sliver of midday sky that showed between the houses. “Here we go! No, that’s not him— Wait, who is that?”

“Quick-change artist,” said Bell. “Turned his coat inside out.”

Their quarry edged from the alley, wearing what appeared to be a light-colored canvas raincoat. He looked around the lane and stepped briskly away.

“I’m getting me one of those,” Joel Wallace whispered.

As the Van Dorns trailed the shadow through Whitechapel, trading the lead, and several times removing their hats and exchanging them with one another, it occurred to Isaac Bell that Jack the Ripper would not have worn gentleman’s clothing when he haunted these streets. Certainly not after the first killing. Even procuring prostitutes, he would have stood out like a sore thumb. He had to have blended with the poor. Or had Ripper outfitted himself with a shabby variant of the shadow’s reversible coat?

“Spotted us!” said Bell. The man had glanced over his shoulder at just the wrong moment and glimpsed Joel Wallace sprinting for a doorway. He ran.

“Get him!” So much for following him back to whoever gave him his orders. They would have to interrogate him instead.

Ironically, they caught up with the shadow on Hanbury Street, and when he sidestepped into an alley, it was not Number 29—but close. Bell tore in after him and grabbed him by his canvas collar.

“I beg your pardon. What do you think you are doing, sir?”

“Interviewing you.”

“Do you know who I am?”

“I will when I’m done.”

“I am a police officer.”

“No you are not,” said Bell. “Police officers work shifts. They spell each other. You’re shadowing me around the clock. You followed me around London; you followed me to Manchester. About the only place you didn’t follow me was into Angel Meadow, where I could have used a hand. Now you’re following me in London, again. All by your lonesome. That makes you a freelance. If you’re freelance, I want to know who’s paying you. If you’re working for Military Intelligence, I want to know what the blazes you think you are doing shadowing an American citizen on legitimate business.”

Bell lifted him an inch off the ground and shook him hard.

“Which is it?”

“I could

have you shot!”

Bell lowered him until his feet touched the mud, loosened one hand, and drew his derringer. “I’m better fixed for shooting.”

He let the operator peer into the immensity of twin barrels, each nearly half an inch wide. “Who are you?”

The man dropped his gaze. “Freelance.”

It was almost certainly a lie, but Bell went along, asking, “Who are you working for?”

“Military Intelligence.”

Bell regarded him sternly. “That is ridiculous. I have nothing to do with Military Intelligence, if such a thing even exists.”

“I’d expect you to deny it.”