On the other hand, he, Theydon, might be balking the course of justice by holding his tongue.  There was yet a third possibility, one fraught with personal discredit.  Mr. Forbes himself might realize that a policy of candor offered the only dignified course.

Suppose he was minded to tell the detectives that he was the man who visited Mrs. Lester shortly before midnight, what would Winter and Furneaux think of the young gentleman who had actually dined with Forbes before they took him into their confidence—­ who heard with such righteous indignation how Mrs. Lester met her death—­ yet brazenly concealed the fact that he had just left the house of one whom they were so anxious to meet and question?

Of course, the radiant vision of Evelyn Forbes intruded on this well-considered and unemotional analysis; but Theydon resolutely shook his head.

“No, by Jove!” he communed.  “You mustn’t make an ass of yourself, my boy, because a pretty girl was gracious for an hour or so.  Be honest with yourself, old chap!  If there were no Evelyn, or if Evelyn were harelipped and squinted, you wouldn’t hesitate a second—­ now, would you?”

Yet he had given a promise.  How reconcile an immediate call on Scotland Yard with the guarantee of secrecy demanded by Forbes?  Well, he must put himself right with Forbes without delay—­ tell him straightforwardly that the bond could not hold.  Theydon was no lawyer, but he was assured that an agreement founded on positive wrong was not tenable, legally or morally.

He would be adamant with Forbes, and decline to countenance any plea in support of continued silence.  If Forbes’s demand was reasonable, Scotland Yard would grant it.  If justice compelled Forbes to come out into the open, no private citizen should attempt to defeat the ends of justice.

“So that settles it,” announced Theydon rmly if not cheerfully.  “I’ll ring up Forbes, and get the thing over and done with.  I’ll never see his daughter again, I suppose, but that can’t be helped. ’tis better to have seen and lost than never to have seen at all.”

He turned from the window, walked to the fireplace, tapped his pipe firmly on the grate, and was about to go into the hall and call up the telephone exchange, when the door-bell rang.  He was aware of a muffled conversation between Bates and a visitor.  Then the valet appeared, obviously ill at ease.

“If you please, sir,” he announced, “a lady, a Miss Beale, of Oxford, who says she is Mrs. Lester’s aunt, wishes to see you.”

Theydon was immensely surprised, as well he might be.  But there was only one thing to be done.

“Show her in,” he said.

Miss Beale entered.  She was slight of figure, middle-aged and gray-haired.  The wanness of her thin features was accentuated by an attire of deep mourning, but the pallor in her cheeks fled for an instant when she set eyes on Theydon.

“Pray forgive the intrusion,” she faltered.  “I—­ I expected to meet an older man.”