The wound was beginning to hurt now. Rutledge warned, "He may not always choose this bridge."

"Yes, sir, I understand that." He shook his head as he bent to retrieve the knife. "A pity. Nothing here to tell us where it came from. Common enough, by the look of it." He ran his finger along the edge. "And sharp enough to bone a chicken."

"I'll come to the station tomorrow to make a statement," Rutledge told him. "Where are you? And what's your name?"

"Lambeth Station. Constable Bishop, sir." He grinned tentatively, adding as if it were a longstanding joke, "Though there are none in the family that I know of."

Rutledge didn't return the smile. He nodded and walked back to where he'd left his motorcar. The blood trickling down his arm to his hand left a trail behind him, and he thought cynically that it was too bad that the boy hadn't cut his own arm instead.

Dr. Lonsdale, answering the summons at his door, was in his dressing gown and still knotting the belt. "It can't wait until morning?" And then he noted the dark patch of blood on Rutledge's sleeve. "Come in, then," he said and led Rutledge directly to his surgery.

"It's not deep," the doctor informed him, turning to wash his hands after examining and then bandaging the wound, "but it will be sore enough for a few days. Be careful how you use it." Accustomed to patching up men from the Yard, he added, "Providing infection doesn't set in from the knife that did this."

It was good advice. The next morning the arm was still sore and felt heavy, but he reported to the Yard, where news of events had preceded him.

Bowles said as they crossed paths in the corridor, "Constable Walker has reported that a week ago on the Lambeth Road a boy tried to rob a doctor returning from a lying-in. Someone came along, and the boy ran. But the description is similar. He claimed he had a knife, but neither the doctor nor his rescuer actually saw it."