“It’s very kind of you to be so concerned about me,” he stammered, “but—­but, Mrs. Bunting, you must excuse me if I say that I do not welcome such solicitude.  I prefer to be left alone.  I—­I cannot stay in your house if I feel that my comings and goings are watched—­spied upon.”

She pulled herself together.  “No one spies upon you, sir,” she said, with considerable dignity.  “I’ve done my best to satisfy you—­”

“You have—­you have!” he spoke in a distressed, apologetic tone.  “But you spoke just now as if you were trying to prevent my doing what I wish to do—­indeed, what I have to do.  For years I have been misunderstood—­persecuted”—­he waited a moment, then in a hollow voice added the one word, “tortured!  Do not tell me that you are going to add yourself to the number of my tormentors, Mrs. Bunting?”

She stared at him helplessly.  “Don’t you be afraid I’ll ever be that, sir.  I only spoke as I did because—­well, sir, because I thought it really wasn’t safe for a gentleman to go out this afternoon.  Why, there’s hardly anyone about, though we’re so near Christmas.”

He walked across to the window and looked out.  “The fog is clearing somewhat; Mrs. Bunting,” but there was no relief in his voice, rather was there disappointment and dread.

Plucking up courage, she followed him.  Yes, Mr. Sleuth was right.  The fog was lifting—­rolling off in that sudden, mysterious way in which local fogs sometimes do lift in London.

He turned sharply from the window.  “Our conversation has made me forget an important thing, Mrs. Bunting.  I should be glad if you would just leave out a glass of milk and some bread-and-butter for me this evening.  I shall not require supper when I come in, for after my walk I shall probably go straight upstairs to carry through a very difficult experiment.”

“Very good, sir.”  And then Mrs. Bunting left the lodger.

But when she found herself downstairs in the fog-laden hall, for it had drifted in as she and her husband had stood at the door seeing Daisy off, instead of going in to Bunting she did a very odd thing —­a thing she had never thought of doing in her life before.  She pressed her hot forehead against the cool bit of looking-glass let into the hat-and-umbrella stand.  “I don’t know what to do!” she moaned to herself, and then, “I can’t bear it!  I can’t bear it!”

But though she felt that her secret suspense and trouble was becoming intolerable, the one way in which she could have ended her misery never occurred to Mrs. Bunting.

In the long history of crime it has very, very seldom happened that a woman has betrayed one who has taken refuge with her.  The timorous and cautious woman has not infrequently hunted a human being fleeing from his pursuer from her door, but she has not revealed the fact that he was ever there.  In fact, it may almost be said that such betrayal has never taken place unless the betrayer has been actuated by love of gain, or by a longing for revenge.  So far, perhaps because she is subject rather than citizen, her duty as a component part of civilised society weighs but lightly on woman’s shoulders.