THE Boston Symphony Orchestra was scheduled that afternoon to play a Bach Concerto and Beethoven's C-Minor Symphony; and Vance, on leaving the District Attorney's office, rode direct to Carnegie Hall. He sat through the concert in a state of relaxed receptivity, and afterward insisted on walking the two miles back to his quarters—an almost unheard-of thing for him.

    Shortly after dinner Vance bade me good night and, donning his slippers and house-robe, went into the library. I had considerable work to do that night, and it was long past midnight when I finished. On the way to my room I passed the library door, which had been left slightly ajar, and I saw Vance sitting at his desk—his head in his hands, the summary lying before him—in an attitude of oblivious concentration. He was smoking, as was habitual with him during any sort of mental activity; and the ash- receiver at his elbow was filled with cigarette-stubs. I moved on quietly, marvelling at the way this new problem had taken hold of him.

    It was half-past three in the morning when I suddenly awoke, conscious of footsteps somewhere in the house. Rising quietly, I went into the hall, drawn by a vague curiosity mingled with uneasiness. At the end of the corridor a panel of light fell on the wall, and as I moved forward in the semi-darkness I saw that the light issued from the partly-open library door. At the same time I became aware that the footsteps, too, came from that room. I could not resist looking inside; and there I saw Vance walking up and down, his chin sunk on his breast, his hands crammed into the deep pockets of his dressing-gown. The room was dense with cigarette- smoke, and his figure appeared misty in the blue haze. I went back to bed and lay awake for an hour. When finally I dozed off it was to the accompaniment of those rhythmic footfalls in the library.

    I rose at eight o'clock. It was a dark, dismal Sunday, and I had my coffee in the living-room by electric light. When I glanced into the library at nine Vance was still there, sitting at his desk. The reading- lamp was burning, but the fire on the hearth had died out. Returning to the living-room, I tried to interest myself in the Sunday newspapers; but after scanning the accounts of the Greene case I lit my pipe and drew up my chair before the grate.

    It was nearly ten o'clock when Vance appeared at the door. All night he had been up, wrestling with his self-imposed problem; and the devitalizing effects of this long, sleepless concentration showed on him only too plainly. There were shadowed circles around his eyes; his mouth was drawn; and even his shoulders sagged wearily. But, despite the shock his appearance gave me, my dominant emotion was one of avid curiosity. I wanted to know the outcome of this all-night vigil; and as he came into the room I gave him a look of questioning expectancy.

    When his eyes met mine he nodded slowly.

    "I've traced the design," he said, holding out his hands to the warmth of the fire. "And it's more horrible than I even imagined." He was silent for some minutes. "Telephone Markham for me, will you, Van? Tell him I must see him at once. Ask him to come to breakfast. Explain that I'm a bit fagged."

    He went out, and I heard him calling to Currie to prepare his bath.

    I had no difficulty in inducing Markham to breakfast with us after I had explained the situation; and in less than an hour he arrived. Vance was dressed and shaved, and looked considerably fresher than when I had first seen him that morning; but he was still pale, and his eyes were fatigued.

    No mention was made of the Greene case during breakfast, but when we had sought easy chairs in the library, Markham could withhold his impatience no longer.

    "Van intimated over the phone that you had made something out of the summary."

    "Yes." Vance spoke dispiritedly. "I've fitted all the items together. And it's damnable! No wonder the truth escaped us."

    Markham leaned forward, his face tense, unbelieving. "You know the truth?"

    "Yes, I know," came the quiet answer. "That is, my brain has told me conclusively who's at the bottom of this fiendish affair; but even now— in the daylight—I can't credit it. Everything in me revolts against the acceptance of the truth. The fact is, I'm almost afraid to accept it... Dash it all, I'm getting mellow. Middle-age has crept upon me." He attempted to smile, but failed.

    Markham waited in silence.

    "No, old man," continued Vance; "I'm not going to tell you now. I can't tell you until I've looked into one or two matters. You see, the pattern is plain enough, but the recognizable objects, set in their new relationships, are grotesque—like the shapes in an awful dream. I must first touch them and measure them to make sure that they're not, after all, mere abortive vagaries."

    "And how long will this verification take?" Markham knew there was no use to try to force the issue. He realized that Vance was fully conscious of the seriousness of the situation, and respected his decision to investigate certain points before revealing his conclusions.

    "Not long, I hope." Vance went to his desk and wrote something on a piece of paper, which he handed to Markham. "Here's a list of the five books in Tobias's library that showed signs of having been read by the nocturnal visitor. I want those books, Markham—immediately. But I don't want anyone to know about their being taken away. Therefore, I'm going to ask you to phone Nurse O'Brien to get Mrs. Greene's key and secure them when no one is looking. Tell her to wrap them up and give them to the detective on guard in the house with instructions to bring them here. You can explain to her what section of the book-shelves they're in."

    Markham took the paper and rose without a word. At the door of the den, however, he paused.

    "Do you think it wise for the man to leave the house?"

    "It won't matter," Vance told him. "Nothing more can happen there at present."

    Markham went on into the den. In a few minutes he returned.

    "The books will be here in half an hour."

    When the detective arrived with the package Vance unwrapped it and laid the volumes beside his chair.

    "Now, Markham, I'm going to do some reading. You won't mind, what?" Despite his casual tone, it was evident that an urgent seriousness underlay his words.

    Markham got up immediately; and again I marvelled at the complete understanding that existed between these two desperate men.

    "I have a number of personal letters to write," he said, "so I'll run along. Currie's omelette was excellent.—When shall I see you again? I could drop round at tea-time."

    Vance held out his hand with a look bordering on affection.

    "Make it five o'clock. I'll be through with my perusings by then. And thanks for your tolerance." Then he added gravely: "You'll understand, after I've told you everything, why I wanted to wait a bit."

    When Markham returned that afternoon a little before five Vance was still reading in the library; but shortly afterward he joined us in the living- room.

    "The picture clarifies," he said. "The fantastic images are gradually taking on the aspect of hideous realities. I've substantiated several points, but a few facts still need corroboration."

    "To vindicate your hypothesis?"

    "No, not that. The hypothesis is self-proving. There's no doubt as to the truth. But—dash it all, Markham! I refuse to accept it until every scrap of evidence has been incontestably sustained."

    "Is the evidence of such a nature that I can use it in a court of law?"

    "That is something I refuse even to consider. Criminal proceedings seem utterly irrelevant in the present case. But I suppose society must have its pound of flesh, and you—the duly elected Shylock of God's great common people—will no doubt wield the knife. However, I assure you I shall not be present at the butchery."

    Markham studied him curiously.

    "Your words sound rather ominous. But if, as you say, you have discovered the perpetrator of these crimes, why shouldn't society exact punishment?"

    "If society were omniscient, Markham, it would have a right to sit in judgment. But society is ignorant and venomous, devoid of any trace of insight or understanding. It exalts knavery, and worships stupidity. It crucifies the intelligent, and puts the diseased in dungeons. And, withal, it arrogates to itself the right and ability to analyze the subtle sources of what it calls 'crime,' and to condemn to death all persons whose inborn and irresistible impulses it does not like. That's your sweet society, Markham—a pack of wolves watering at the mouth for victims on whom to vent its organized lust to kill and flay."

    Markham regarded him with some astonishment and considerable concern.

    "Perhaps you are preparing to let the criminal escape in the present case," he said with the irony of resentment.

    "Oh, no," Vance assured him. "I shall turn your victim over to you. The Greene murderer is of a particularly vicious type, and should be rendered impotent. I was merely trying to suggest that the electric chair—that touchin' device of your beloved society—is not quite the correct method of dealing with this culprit."

    "You admit, however, that he is a menace to society."

    "Undoubtedly. And the hideous thing about it is that this tournament of crime at the Greene mansion will continue unless we can put a stop to it. That's why I am being so careful. As the case now stands, I doubt if you could even make an arrest."

    When tea was over Vance got up and stretched himself.

    "By the by, Markham," he said off-handedly, "have you received any report on Sibella's activities?"

    "Nothing important. She's still in Atlantic City, and evidently intends to stay there for some time. She phoned Sproot yesterday to send down another trunkful of her clothes."

    "Did she, now? That's very gratifyin'." Vance walked to the door with sudden resolution. "I think I'll run out to the Greenes' for a little while. I shan't be gone over an hour: Wait for me here, Markham—there's a good fellow; I don't want my visit to have an official flavour. There's a new Simplicissimus on the table to amuse you till I return. Con it and thank your own special gods that you have no Thony or Gulbranssen in this country to caricature your Gladstonian features."

    As he spoke he beckoned to me, and, before Markham could question him, we passed out into the hall and down the stairs. Fifteen minutes later a taxicab set us down before the Greene mansion.

    Sproot opened the door for us, and Vance, with only a curt greeting, led him into the drawing-room.

    "I understand," he said, "that Miss Sibella phoned you yesterday from Atlantic City and asked to have a trunk shipped to her."

    Sproot bowed. "Yes, sir. I sent the trunk off last night."

    "What did Miss Sibella say to you over the phone?" "Very little, sir—the connection was not good. She said merely that she had no intention of returning to New York for a considerable time and needed more clothes than she had taken with her."

    "Did she ask how things were going at the house here?"

    "Only in the most casual way, sir."

    "Then she didn't seem apprehensive about what might happen here while she was away?"

    "No, sir. In fact—if I may say so without disloyalty—her tone of voice was quite indifferent, sir."

    "Judging from her remarks about the trunk, how long would you say she intends to be away?"

    Sproot considered the matter.

    "That's difficult to say, sir. But I would go so far as to venture the opinion that Miss Sibella intends to remain in Atlantic City for a month or more."

    Vance nodded with satisfaction.

    "And now, Sproot," he said, "I have a particularly important question to ask you. When you first went into Miss Ada's room on the night she was shot and found her on the floor before the dressing-table, was the window open? Think! I want a positive answer. You know the window is just beside the dressing-table and overlooks the steps leading to the stone balcony. Was it open or shut?"

    Sproot contracted his brows and appeared to be recalling the scene. Finally he spoke, and there was no doubt in his voice.

    "The window was open, sir. I recall it now quite distinctly. After Mr. Chester and I had lifted Miss Ada to the bed, I closed it at once for fear she would catch cold."

    "How far open was the window?" asked Vance with eager impatience.

    "Eight or nine inches, sir, I should say. Perhaps a foot." "Thank you, Sproot. That will be all. Now please tell the cook I want to see her."

    Mrs. Mannheim came in a few minutes later, and Vance indicated a chair near the desk-light. When the woman had seated herself he stood before her and fixed her with a stern, implacable gaze.

    "Frau Mannheim, the time for truth-telling has come. I am here to ask you a few questions, and unless I receive a straight answer to them I shall report you to the police. You will, I assure you, receive no consideration at their hands."

    The woman tightened her lips stubbornly and shifted her eyes, unable to meet Vance's penetrating stare.

    "You told me once that your husband died in New Orleans thirteen years ago. Is that correct?"

    Vance's question seemed to relieve her mind, and she answered readily.

    "Yes, yes. Thirteen years ago."

    "What month?"

    "In October."

    "Had he been ill long?"

    "About a year."

    "What was the nature of his illness?"

    Now a look of fright came into her eyes.

    "I—don't know—exactly," she stammered. "The doctors didn't let me see him."

    "He was in a hospital?"

    She nodded several times rapidly. "Yes—a hospital."

    "And I believe you told me, Frau Mannheim, that you saw Mr. Tobias Greene a year before your husband's death. That would have been about the time your husband entered the hospital—fourteen years ago."

    She looked vaguely at Vance, but made no reply.

    "And it was exactly fourteen years ago that Mr. Greene adopted Ada."

    The woman caught her breath sharply. A look of panic contorted her face.

    "So when your husband died," continued Vance, "you came to Mr. Greene, knowing he would give you a position."

    He went up to her and touched her filially on the shoulder.

    "I have suspected for some time, Frau Mannheim," he said kindly, "that Ada is your daughter. It's true, isn't it?"

    With a convulsive sob the woman hid her face in her apron.

    "I gave Mr. Greene my word," she confessed brokenly, "that I wouldn't tell anyone—not even Ada—if he let me stay here—to be near her."

    "You haven't told anyone," Vance consoled her. "It was not your fault that I guessed it."

    When Mrs. Mannheim left us a little later Vance had succeeded in allaying her apprehension and distress. He then sent for Ada.

    As she entered the drawing-room the troubled look in her eyes and the pallor of her cheeks told clearly of the strain she was under. Her first question voiced the fear uppermost in her mind.

    "Have you found out anything, Mr. Vance?" She spoke with an air of pitiful discouragement. "It's terrible alone here in this big house— especially at night. Every sound I hear..."

    "You mustn't let your imagination get the best of you, Ada," Vance counselled her. Then he added: "We know a lot more now than we did, and before long, I hope, all your fears will be done away with. In fact, it's in regard to what we've found out that I've come here to-day. I thought perhaps you could help me again."

    "If only I could! But I've thought and thought..."

    Vance smiled.

    "Let us do the thinking, Ada.—What I wanted to ask you is this: do you know if Sibella speaks German well?" The girl appeared surprised.

    "Why, yes. And so did Julia and Chester and Rex. Father insisted on their learning it. And he spoke it too—almost as well as he spoke English. As for Sibella, I've often heard her and Doctor Von Blon talking in German."

    "But she spoke with an accent, I suppose."

    "A slight accent—she'd never been long in Germany. But she spoke German very well."

    "That's what I wanted to be sure of."

    "Then you do know something!" Her voice quavered with eagerness. "Oh, how long before this awful suspense will be over? Every night for weeks I've been afraid to turn out my lights and go to sleep."

    "You needn't be afraid to turn out your lights now," Vance assured her. "There won't be any more attempts on your life, Ada."

    She looked at him for a moment searchingly, and something in his manner seemed to hearten her. When we took our leave the colour had come back to her cheeks.

    Markham was pacing the library restlessly when we arrived home.

    "I've checked several more points," Vance announced. "But I've missed the important one—the one, that would explain the unbelievable hideousness of the thing I've unearthed."

    He went directly into the den, and we could hear him telephoning. Returning a few minutes later, he looked anxiously at his watch. Then he rang for Currie and ordered his bag packed for a week's trip.

    "I'm going away, Markham," he said. "I'm going to travel—they say it broadens the mind. My train departs in less than an hour; and I'll be away a week. Can you bear to be without me for so long? However, nothing will happen in connection with the Greene case during my absence. In fact, I'd advise you to shelve it temporarily."

    He would say no more, and in half an hour he was ready to go.

    "There's one thing you can do for me while I'm away," he told Markham, as he slipped into his overcoat. "Please have drawn up for me a complete and detailed weather report from the day preceding Julia's death to the day following Rex's murder."

    He would not let either Markham or me accompany him to the station, and we were left in ignorance of even the direction in which his mysterious trip was to take him.