Vendors cursed as Luke pounded by, pursued hard by Mr. Fielding. Daniel boiled out of an alley behind a hotel that backed onto the market, nearly into Luke’s path. The man checked himself and changed direction, but I sprinted through gaps in the stalls, landing directly in front of Luke as he barreled through.

“Stop!” I shouted, my hands up.

I do not know why I thought Luke would obey. He could easily slam me aside, and there wasn’t a thing I could do to stop him.

In the next moment, Daniel felled him with a running tackle. Mr. Fielding burst from the stalls where he’d fallen behind as Daniel and Luke began to fight.

I’d seen Daniel in combat before, but then he’d pretended to falter and lose, in order to preserve a disguise. This time, he fought in earnest, his fists flying, boots kicking, not missing a trick. No rules or gentlemanly behavior for Daniel—he fought to win.

Mr. Fielding snatched up a loose board and stepped toward the tumbling mass of Daniel and Luke, ready to strike. The men moved too fast, however, and Mr. Fielding might hit Daniel instead.

And that is just what Mr. Fielding did. The board came down, slashing Daniel across the back of the head. Daniel fell as I cried out, losing his grip on Luke. Daniel landed on his back, and Luke took advantage and sprang away.

“He’s mine, damn you.” Mr. Fielding glared at Daniel and dashed after Luke, tossing away the board as he went.

“You bloody fool!” Daniel roared, but Mr. Fielding was gone.

I helped Daniel to his feet. He pressed his hand to the back of his head, and his fingers came away red. The vendors who’d witnessed the fight surged forward to assist, but Daniel waved them off.

“I’m fine.” He took a few steps, but I clung to him.

“Sit down. He’s hurt you.”

Daniel gently dislodged my grasp. “He’s maddened. We need to stop him.”

I agreed, but a blow to the head could be perilous. Daniel, however, started away, his steps even. I went right after him.

Together we pursued Mr. Fielding and Luke down Southampton Street. If they reached the Strand at the end, Luke might be lost in the crush of traffic, and again, could reach railway stations that would put him far out of reach.

Daniel smiled as we entered Southampton Street, cracking the sweat and soot on his face. He brought a police whistle out of his pocket and blew it.

More whistles sounded in response, the bobbies of Covent Garden answering Daniel’s summons. Constables surged down Southampton Street, and more ran in from the Strand at the other end. They surrounded Luke just as Mr. Fielding caught him.

Mr. Fielding’s cry of rage rang through the dimming afternoon. He raised his fist and smashed it into Luke’s face, and raised it again.