the ticket. Yes, by all means." He opened the envelope and, turning its contents out on the bench, picked up the dingy slip of paper. After a glance at it he handed it to me. It was punched for the journey from Tooley Street to Dockhead.
"Another coincidence," he remarked; "and by yet another, I think I hear Miller knocking at our door."
It was the superintendent, and, as we let him into the room, the hum of a motor-car entering from Tudor Street announced the arrival of Mrs. Chater. We waited for her at the open door, and, as she entered, she held out her hands impulsively.
"Say, now, Dr. Thorndyke," she exclaimed, "have you gotten something to tell us?"
"I have a suggestion to make," replied Thorndyke. "I think that if the superintendent will take this key to Hanover Buildings, Dockhead, Bermondsey, he may possibly find a door that it will fit."
"The deuce!" exclaimed Miller. "I beg your pardon, madam; but I thought I had gone through that coat pretty completely. What was it that I had overlooked, sir? Was there a letter hidden in it, after all?"
"You overlooked the dust on it, Miller; that is all," said Thorndyke.
"Dust!" exclaimed the detective, staring round-eyed at my colleague. Then he chuckled
