Theydon was literally astounded, and did not strive to hide his agitation. But he was by no means tongue-tied. Now, most emphatically, was he determined to have done with pretense. Whether by accident or design, Forbes had placed himself with his back to the window.

The younger man deliberately crossed the room, pulled up the blind, thus admitting the flood of light which comes only from the upper third of a window, and sat down in such a position that Forbes was compelled to turn in order to face him.

"Before you utter another word, Mr. Forbes," he said gravely, "let me tell you that in my efforts to trace your whereabouts I also called up Fortescue Square. Miss Forbes came to the telephone. She said you had gone to the Home Office. By some feminine necromancy, too, she divined the link which binds you with the death of Mrs. Lester. She was distressed on your account, and I was hard put to it to extricate myself from the risk of saying something which I might regret. I--"

"What do you imply by that remark?" interrupted Forbes, piercing the other with a look that was strangely reminiscent of his daughter's candid scrutiny.

"I imply the serious fact that I know who visited Mrs. Lester before she met her death. I not only heard her visitor's arrival and departure, but saw him at the corner of these mansions while on my way home from Daly's Theater, and again when he posted a letter in the pillar box on the same corner. If such unwonted interest on my part in the movements of one who was then a complete stranger surprises you, let me remind you that only a few minutes earlier I had stood by his side at the door of the theater and heard him telling his daughter that he intended to walk to the Constitutional Club."

Forbes smiled, but uttered no word. His expression was inscrutable. His pallor reminded Theydon of the tint of ivory, of that waxen-white Dutch grisaille beloved of fifteenth century illuminators of manuscripts. His silence was disturbing, almost irritating, his manner singularly calm.

These negative indications conveyed absolutely nothing to Theydon, who for the second time in their brief acquaintance found himself in the ridiculous position of one explaining a fault rather than, as he imagined, arraigning a man under suspicion.

"So we had better dispense with ambiguities, Mr. Forbes," he went on, speaking with a precision that sounded oddly in his own ears. "It was you who called on Mrs. Lester on Monday night, you who posted the letter she wrote to Miss Beale at Iffley, Oxfordshire, you for whom the police are now searching. I have contrived thus far to keep your secret, but the situation is passing out of my control. I would help you if I could--"

"Why?"

The monosyllable, sharp and insistent, was disconcerting as the unexpected crack of a whip, but Theydon answered valiantly:

"Because of the monstrous absurdities with which Fate has plagued me during the past two days, I appeal now for outspokenness, so I set an example. Had it not been for your daughter's remarkably attractive appearance I should not, in all likelihood, have given a second glance at my neighbors on the steps of the theater. But I cannot forget that I did see both her and you--indeed, Miss Forbes herself recalled the incident--and the close questioning of the Scotland Yard men who were here last night showed me the folly of imagining that I could deny all knowledge of you. I recognize now that some impish contriving of circumstances forced this knowledge upon me. The sudden downpour of rain, and the fact that I was delayed by a slight accident to my cab, conspired with the apparently simple chance which led me to overhear the conversation between Miss Forbes and yourself. I tried hard to baffle the detectives--"

"Again I ask 'Why?'"

Theydon was rapidly being wound up to a pitch of excited resentment.

"Why?" he cried. "Was I not your guest? How could I come from a house where I had been admitted to a delightful intimacy and tell the representatives of the law that my host was the man they were looking for?"

During some seconds Forbes bent his eyes on the floor, seemingly in deep thought.

"Theydon," he said at last, looking up in his direct way, "I am your senior by a good many years--am old enough, as the saying goes, to be your father. I may venture, therefore, to give you a piece of sound advice. Pack a kit-bag, catch the afternoon boat train for Boulogne, and go for a walking tour in Normandy and Brittany. When I was your age and a junior in a bank I had to take my holidays in May; each year I tramped that corner of France. I recommend it as a playground. It will appeal to your literary instincts, and it has the immeasurable advantage just now of being practically as remote from London as the Sahara."

It must not be forgotten that Theydon was a romancer, an idealist. The "lounge suit" of the modern tailor hampers the play of such qualities no more than the beaten armor of the age of chivalry.

"If my departure for France will relieve Miss Forbes of anxiety on your behalf, I'll go," he vowed.

Forbes regarded him with a new interest.

"I believe you mean that," he said.

"I do."

"But I cannot send you out of the country on a false pretense. It was your safety and well-being, not my daughter's, that I was thinking of."

"What have I to fear?"

"I do not know. I am like a man wandering by night in a jungle alive with fearsome beasts and reptiles."

"Yet you had some reason for suggesting my prompt departure."

"Yes. It is an absurd thing to say, but I believe I am putting you in danger of your life by coming here this morning."

"Can't you speak plainly, Mr. Forbes? What good purpose do you serve by holding forth these vague terrors? If, as Miss Forbes told me, you have visited the Home Office, I take it you made yourself clear to the authorities--assuming, that is, you went there in connection with the amazing conditions which seem to be bound up with this crime."

"There is a certain class of knowledge which is in itself dangerous to those who possess it, no matter whether or not it affects them in any particular. I recommend you, in good faith, to leave London today."

"If my own safety is the only consideration I refuse as readily as I agreed before."

Theydon's tone grew somewhat impatient. He really fancied that Forbes was trifling with him. Indeed, a queer doubt of the man's complete sanity now peeped up in him. Forbes was regarded as a crank by a large section of the public on account of his peace propaganda; if that opinion were justified why should he not be eccentric in other respects?

It was fantastic, almost stupid, to look upon him as responsible for Mrs. Lester's murder, but there was always a possibility that he might be utilizing the chance which led him to her apartments shortly before the crime was committed to cover himself and his movements with a veil of spurious mystery. In a word, though Theydon had likened his visitor's face to a mask of ivory he had momentarily forgotten the ominous token found on Mrs. Lester's body and duplicated in Forbes's own house by the morning's post.

Forbes spread wide his hands with the air of one who heard, but was allowing his thoughts to wander. When next he spoke it was only to increase the crazy inconsequence of their talk.

"Later--perhaps today--perhaps it may never be necessary--I may explain myself to your heart's content," he said slowly. "At present I am here to ask a favor. In the first place, is Mrs. Lester's flat in charge of the police?"

"I suppose so," said Theydon.

"Is there a detective or constable on duty there now?"

"I am not sure. I imagine there is not. When the Scotland Yard men and I came out after midnight they locked the door and took away the key.

The--er--body is at the mortuary, awaiting the opening of the inquest at three o'clock."

"Ah! I hoped that would be so. Can you ascertain for certain?"

"But why?"

"Because I wish to go in there. And that brings me to the favor I seek.

The secretary of these flats, even the hall porter, should have a master key. Borrow it on some pretext. They will give it to you."

"Really, Mr. Forbes--" gasped Theydon, voicing his surprise as a preliminary to a decided refusal. He was interrupted by the insistent clang of the telephone--that curt herald which brooks no delay in answering its demand for an audience.

"Pardon me one moment," he said. "I'll just see who that is."

The inquirer was Evelyn Forbes.

"I've waited patiently--" she began, but he stopped her instantly by saying that her father was with him.

"Please ask him to come to the phone," she said.

Forbes rose at once. He merely assured the girl that he was engaged in important business and would be home soon after the luncheon hour.

Meanwhile, she was not to go out, and his orders must be obeyed to the letter.

"Now, Theydon," he said, coming back to the sitting room, "what about that key?"

The most extraordinary feature of an extraordinary case was the way in which the mere sound of Evelyn Forbes's voice stilled any qualms of conscience in Theydon's breast. He knew he was acting foolishly in conducting a blind inquiry on his own account, an inquiry which might well arouse the anger and active resentment of the police, but he offered a sop to his better judgment by consulting Bates.

Then came a veritable surprise.

"The fact is, sir," admitted Bates nervously, "we have Ann Rogers's key in the kitchen. When she went away on Monday she left it here, bein'