“Please wait till this evening,” he said hastily.  “It is my custom to stay at home all day.  I only care to walk about the streets when the lights are lit.  You must bear with me, Mrs. Bunting, if I seem a little, just a little, unlike the lodgers you have been accustomed to.  And I must ask you to understand that I must not be disturbed when thinking out my problems—­” He broke off short, sighed, then added solemnly, “for mine are the great problems of life and death.”

And Mrs. Bunting willingly fell in with his wishes.  In spite of her prim manner and love of order, Mr. Sleuth’s landlady was a true woman —­she had, that is, an infinite patience with masculine vagaries and oddities.

When she was downstairs again, Mr. Sleuth’s landlady met with a surprise; but it was quite a pleasant surprise.  While she had been upstairs, talking to the lodger, Bunting’s young friend, Joe Chandler, the detective, had come in, and as she walked into the sitting-room she saw that her husband was pushing half a sovereign across the table towards Joe.

Joe Chandler’s fair, good-natured face was full of satisfaction:  not at seeing his money again, mark you, but at the news Bunting had evidently been telling him—­that news of the sudden wonderful change in their fortunes, the coming of an ideal lodger.

“Mr. Sleuth don’t want me to do his bedroom till he’s gone out!” she exclaimed.  And then she sat down for a bit of a rest.

It was a comfort to know that the lodger was eating his good breakfast, and there was no need to think of him for the present.  In a few minutes she would be going down to make her own and Bunting’s dinner, and she told Joe Chandler that he might as well stop and have a bite with them.

Her heart warmed to the young man, for Mrs. Bunting was in a mood which seldom surprised her—­a mood to be pleased with anything and everything.  Nay, more.  When Bunting began to ask Joe Chandler about the last of those awful Avenger murders, she even listened with a certain languid interest to all he had to say.

In the morning paper which Bunting had begun taking again that very day three columns were devoted to the extraordinary mystery which was now beginning to be the one topic of talk all over London, West and East, North and South.  Bunting had read out little bits about it while they ate their breakfast, and in spite of herself Mrs. Bunting had felt thrilled and excited.

“They do say,” observed Bunting cautiously, “They do say, Joe, that the police have a clue they won’t say nothing about?” He looked expectantly at his visitor.  To Bunting the fact that Chandler was attached to the detective section of the Metropolitan Police invested the young man with a kind of sinister glory—­especially just now, when these awful and mysterious crimes were amazing and terrifying the town.

“Them who says that says wrong,” answered Chandler slowly, and a look of unease, of resentment came over his fair, stolid face.  “’Twould make a good bit of difference to me if the Yard had a clue.”