“Or in damp weather?” said Stone.  “Mr. Hall, I have questioned you enough.  I will now tell these gentlemen, since you refuse to do so, where you were on the night of Mr. Crawford’s murder.  You were not in West Sedgwick, or near it.  You are absolutely innocent of the crime or any part in it.”

Gregory Hall straightened up perceptibly, like a man exonerated from all blame.  But he quailed again, as Fleming Stone, looking straight at him, continued:  “You left West Sedgwick at six that evening, as you have said.  You registered at the Metropolis Hotel, after learning that you could not get a room at your club.  And then—­you went over to Brooklyn to meet, or to call on, a young woman living in that borough.  You took her back to New York to the theatre or some such entertainment, and afterward escorted her back to her home.  The young woman wore a street costume, by which I mean a cloth gown without a train.  You did not have a cab, but, after leaving the car, you walked for a rather long distance in Brooklyn.  It was raining, and you were both under one umbrella.  Am I correct, so far?”

At last Gregory Hall’s calm was disturbed.  He looked at Fleming Stone as at a supernatural being.  And small wonder.  For the truth of Stone’s statements was evident from Hall’s amazement at them.

“You—­you saw us!” he gasped.

“No, I didn’t see you; it is merely a matter of observation, deduction, and memory.  You recollect the muddy shoes?” he added, turning to me.

Did I recollect!  Well, rather!  And it certainly was a coincidence that we had chanced to examine those shoes that morning at the hotel.

As for Mr. Randolph and the district attorney, they were quite as much surprised as Hall.

“Can you prove this astonishing story, Mr. Stone?” asked Mr. Goodrich, with an incredulous look.

“Oh, yes, in lots of ways,” returned Stone.  “For one thing, Mr. Hall has in his pocket now a letter from the young lady.  The whole matter is of no great importance except as it proves Mr. Hall was not in West Sedgwick that night, and so is not the murderer.”

“But why conceal so simple a matter?  Why refuse to tell of the episode?” asked Mr. Randolph.

“Because,” and now Fleming Stone looked at Hall with accusation in his glance—­“because Mr. Hall is very anxious that his fiancee shall not know of his attentions to the young lady in Brooklyn.”

“O-ho!” said Mr. Goodrich, with sudden enlightenment.  “I see it all now.  Is it the truth, Mr. Hall?  Did you go to Brooklyn and back that night, as Mr. Stone has described?”

Gregory Hall fidgeted in an embarrassed way.  But, unable to escape the piercing gaze of Stone’s eyes, he admitted grudgingly that the detective had told the truth, adding, “But it’s wizardry, that’s what it is!  How could he know?”

“I had reason for suspicion,” said Stone; “and when I found you were deaf in your right ear, and that you had in your pocket a letter addressed in a feminine hand, and postmarked `Brooklyn,’ I was sure.”