Forbes, not without a perceptible effort, choked down his wrath and recovered his poise.

“You have gaged the state of affairs accurately enough,” he said, speaking more calmly.  “May I, then, recommend you to consult your direct superiors before carrying your investigations any furthur, Mr.—­”

“Furneaux—­ Charles Francois Furneaux.”

“Just so, Mr. Charles Francois Furneaux.”

“I give you my full name, because one of the peculiar features of this case is the inability of some persons mixed up in it to recall names, or even the mere salient facts,” and the detective’s glance dwelt for an instant on Theydon, who, again, in his own estimation, shrank into the boots of a fourth-form boy detected by a master in an overt breach of college rules.

But the little man was speaking impressively, and, Theydon compelled his wandering wits to pay attention.

“It will clear the air, perhaps,” went on Furneaux, “if I point out that if any one here is playing the spy—­ carrying on some underhanded game, that is—­ it is not I. These apartments are in charge of the police.  The manager of the whole block of flats and the porter of this particular section have been warned that no one can be allowed to enter No. 17, on any pretext, until our inquiry is closed.  Now, Mr. Forbes, kindly explain how you contrived to get possession of a key.”

An experienced man of the world like Forbes could hardly fail to see that he was in a false position, and that any persistent attempt to browbeat the detective would not only meet with utter failure but might possibly compromise him gravely.

“That was a simple matter,” he said.  “Mrs. Lester’s servant left her key in Mr. Theydon’s establishment.  Bates surprised both his master and me by producing it when I expressed a wish to examine the place.”

“But why adopt such a clandestine method?”

Forbes’s face, usually so classic in outline, assumed a certain rigidity, and his firm chin grew markedly aggressive.

“I don’t answer questions put in that way,” he said.

Furneaux laughed sardonically.

“You meet with greater respect in Capel Court, I have no doubt,” he snapped.  “There you stand on a pedestal, with one hand flourishing a check-book and the other resting gracefully on the neck of a golden calf.  Here, you are simply an ordinary citizen behaving in a suspicious manner.  If the uniformed policeman on the neighboring beat knew what I know of your recent movements he would arrest you without ceremony, and charge you with being concerned in the murder of Mrs. Lester.  Between you and Mr. Theydon, the work of my department has been hindered and burked most scandalously.  Don’t glare at me like that!  I don’t care tuppence for your millions and your social position.  What I do care about is the horrible risk you and each member of your family are incurring.  You know why, and while you are still alive I mean to force you to speak.  Tell me now why Mrs. Lester was killed.  Tell me, too, why the same hand which thrust a little ivory skull into the dead woman’s underbodice caused a similar token to be delivered to you by this morning’s post.  Ah, that touches you, does it?  Now, my worthy financier and philanthropist, step down from your pedestal and behave like a being of flesh and blood!”