Straightway Bobby repented the alarm he had, perhaps too impulsively, given. For the hand protruding from the wall was, indeed, flesh and blood, and with the knowledge came back his fear for Katherine, conquering his first relief. A sick revulsion swept him. He remembered the evidence found in Katherine's room, and her refusal to answer questions. Could Paredes and the officers have been right? Was it conceivably her hand struggling weakly in his grasp?

The door from the corridor crashed open. Rawlins burst through. Graham ran after him. From the private stairway arose the sound of the district attorney's hurrying footsteps.

"What is it? What have you got?" Rawlins shouted.

Graham cried out:

"You're all right, Bobby?"

The candle which the detective carried gleamed on the slender fingers, showing Bobby that they had been inserted through an opening in the wall. He couldn't understand, for time after time each one of the panels had been sounded and examined. Beyond, he could see dimly the dark clothing of the person who, with a stealth in itself suggestive of abnormal crime, had made use of such a device. As Rawlins hurried up he wondered if it wouldn't be the better course to free his prisoner, to cry out, urging an escape.

Already it was too late. The detective and Graham had seen, and clearly they had no doubt that he held the one responsible for two brutal murders and for the confusing mysteries that had capped them.

"Looks like a lady's hand," Rawlins called. "Don't let go, young fellow."

He unlocked the door to the private hallway. Graham and he dashed out. In
Bobby's uncertain grasp the hand twitched.

Robinson's voice reached him through the opening.

"Let go, Mr. Blackburn. You've done your share, the Lord knows. You've caught the beast with the goods."

Bobby released the slender fingers. He saw them vanish through the opening. He left the bed and reluctantly approached the door to the private hall. Excited phrases roared in his ears. He scarcely dared listen because of their possible confirmation of his doubt. The fingers, he repeated to himself, had been too slender. The moment that had freed him from fear of his own guilt had constructed in its place an uncertainty harder to face. Yet there was nothing to be gained by waiting. Sooner or later he must learn whether Katherine had hidden the evidence, whether she had used the stout and deadly hatpin, whether she struggled now in the grasp of vindictive men.

A voice from the corridor arrested him.

"Bobby!"

With a glad cry he swung around. Katherine stood in the opposite doorway. Her presence there, beyond a doubt, was her exculpation. He crossed the sombre room. He grasped her hands. He smiled happily. After all, the hand he had held was not as slender as hers.

"Thank heavens you're here."

In a word he recited the result of his vigil.

"It clears you," she said. "Quick! We must see who it is."

But he lingered, for he wanted that ugly fear done with once for all.

"You can tell me now how the evidence got in your room."

"I can't," she said. "I don't know."

The truth of her reply impressed him. He looked at her and wondered that she should be fully dressed.

"Why are you dressed?" he asked.

She was puzzled.

"Why not? I don't think any one had gone to bed."

"But it must be very late. I supposed it was the same time—half-past two."

She started to cross the room. She laughed nervously.

"It isn't eleven."

He recalled his interminable anticipation among the shadows of the old room.

"I've watched there only a little more than an hour!"

"Not much more than that, Bobby."

"What a coward! I'd have sworn it was nearly daylight."

She pressed his hand.

"No. Very brave," she whispered. "Let us see if it was worth it."

They stepped through the doorway. Half way down the hall Robinson, Graham, and Rawlins held a fourth, who had ceased struggling. Bobby paused, yet, since seeing Katherine step from the corridor, his reason had taught him to expect just this.

The fourth man was Paredes, nearly effeminate, slender-fingered.

"Carlos!" Bobby cried. "You can't have done these unspeakable things!"

The Panamanian stared without answering. Evidently he had had time to control his chagrin, to smother his revolt from the future; for the thin face was bare of emotion. The depths of the eyes as usual turned back scrutiny. The man disclosed neither guilt nor the outrage of an assumed innocence; neither confession nor denial. He simply stared, straining a trifle against the eager hands of his captors.

Rawlins grinned joyously.

"You ought to have a medal for getting away with this, young fellow.
Things didn't look so happy for you an hour or so ago."

"And I had half a mind," Robinson confessed, "to refuse you the chance.
Glad I didn't. Glad as I can be you made good."

With the egotism any man is likely to draw from his efforts in the detection of crime he added easily:

"Of course I've suspected this spigotty all along. I don't have to remind you of that."

"Sure," Rawlins said. "And didn't I put it up to him strong enough to-night?"

Paredes laughed lightly.

"All credit where it is due. You also put it up to Miss Perrine."

"The details will straighten all that out," Robinson said. "I don't pretend to have them yet."

"I gather not," Paredes mused, "with old Blackburn's ghost still in the offing."

"That talk," Rawlins said, "won't go down from you any more. I daresay you've got most of the details in your head."

"I daresay," Paredes answered dryly.

He fought farther back against the detaining hands.

"Is there any necessity for this exhibition of brute strength? You must find it very exhausting. You may think me dangerous, and I thank you; but I have no gun, and I'm no match for four men and a woman. Besides, you hurt my arm. Bobby was none too tender with that. I ought to have used my good arm. You'll get no details from me unless you take your hands off."

Robinson's hesitation was easily comprehensible. If Paredes were responsible for the abnormalities they had experienced at the Cedars he might find it simple enough to trick them now, but the man's mocking smile brought the anger to Robinson's face.

"Of course he can't get away. See if there's anything on his clothes,
Rawlins. He ought to have the hatpin. Then let him go."

The detective, however, failed to find the hatpin or any other weapon.

"You see," Paredes smiled. "That's something in my favour."

He stepped back, brushing his clothing with his uninjured hand. He lighted a cigarette. He drew back the coat sleeve of his left arm and readjusted the bandage. He glanced up as heavy footsteps heralded Doctor Groom.

"Hello, Doctor," he called cheerily. "I was afraid you'd nap through the show. It seems the bloodhounds of the law left us out of their confidence."

"What's all this?" the doctor rumbled.

Paredes waved his hand.

"I am a prisoner."

The doctor gaped.

"You mean you—"

"Young Blackburn caught him," Robinson explained. "He was in a position to finish him just as he did Howells."

"Except that I had no hatpin," Paredes yawned.

The doctor's uneasy glance sought the opening in the wall.

"I thought you had examined all these walls," he grumbled. "How did you miss this?"

Robinson ran his fingers through his hair.

"That's what I've been asking myself," he said. "I went over that panelling a dozen times myself."

Bobby and Katherine went closer. Bobby had been from the first puzzled by Paredes's easy manner. He had a quick hope. He saw the man watch with an amused tolerance while the district attorney bent over, examining the face of the panel.

"An entire section," Robinson said—"the thickness of the wall—has been shifted to one side. No wonder we didn't see any joints or get a hollow sound from this panel any more than from the others. But why didn't we stumble on the mechanism? Maybe you'll tell us that, Paredes."

The Panamanian blew a wreath of smoke against the ancient wall.

"Gladly, but you will find it humiliating. I have experienced humility in this hall myself. The reason you didn't find any mechanism is that there wasn't any. You looked for something most cautiously concealed, not realizing that the best concealment is no concealment at all. It's fundamental. I don't know how it slipped my own mind. No grooves show because the door is an entire panel. There isn't even a latch. You merely push hard against its face. Such arrangements are common enough in colonial houses, and there was more than the nature of the crimes to tell you there was some such thing here. I mean if you will examine the farther door closer than you have done you will find that it has fewer coats of paint than the one leading to the corridor, that its frame is of newer wood. In other words, it was cut through after the wing was built. This panel was the original door, designed, with the private stairway and the hall, for the exclusive use of the master of the house. Try it."

Robinson braced himself and shoved against the panel. It moved in its grooves with a vibrant stirring.

"Rusty," he said.

Katherine started.

"That's what I heard each time," she cried.

Above his heavy black beard the doctor's cheeks whitened. Robinson made a gesture of revulsion.

"That gives the nasty game away."

"Naturally," Paredes said, "and you must admit the game is as beautifully simple as the panel. The instrument of death wasn't inserted through the bedding as you thought inevitable, Doctor. Suppose you were lying in that bed, asleep, or half asleep, and you were aroused by such a sound as that in the wall behind you? What would you do? What would any man do first of all?"

Robinson nodded.

"I see what you mean. I'd get up on my elbow. I'd look around as quickly as I could to see what it was. I'd expose myself to a clean thrust. I'd drop back on the bed, more thoroughly out of it than though I'd been struck through the heart."

"Exactly," Paredes said, with the familiar shrug of his shoulders.

"You're sensible to give up this way," Robinson said. "It's the best plan for you. What about Mr. Blackburn?"

Graham interfered.

"After all," he said thoughtfully. "I'm a lawyer, and it isn't fair, Robinson. It's only decent to tell him that anything he says may be used against him."

"Keep your mouth shut," Robinson shouted.

But Paredes smiled at Graham.

"It's very good of you, but I agree with the district attorney. There's no point in being a clam now."

"Can you account for Silas Blackburn's return?" the doctor asked eagerly.

"That's right, Doctor," Paredes said. "Stick to the ghosts. I fancy there are plenty in this house. I'm afraid we must look on Silas Blackburn as dead."

"You don't mean we've been talking to a dead man?" Katherine whispered.

"Before I answer," Paredes said, "I want to have one or two things straight. These men, Bobby, I really believe, think me capable of the crimes in this house. I want to know if you accept such a theory. Do you think I had any idea of killing you?"

Bobby studied the reserved face which even now was without emotion.

"I can't think anything of the kind," he said softly.

"That's very nice," Paredes said. "If you had answered differently I'd have let these clever policemen lay their own ghosts."

He turned to Robinson.

"Even you must begin to see that I'm not guilty. Your common sense will tell you so. If I had been planning to kill Bobby, why didn't I bring the weapon? Why did I put my hand through the opening before I was ready to strike? Why did I use my left hand—my injured hand? I was like Howells. I couldn't consider the case finished until I had solved the mystery of the locked doors. I supposed the room was empty. When I found the secret to-night, I reached through to see how far my hand would be from the pillow."

Bobby's assurance of Paredes's innocence clouded his own situation; made it, in a sense, more dangerous than it had ever been. His wanderings about the Cedars remained unexplained, and they knew now it had never been necessary for the murderer to enter the room, Katherine, too, evidently realized the menace.

"Do you think I—" she began.

Paredes bowed.

"You dislike me, Miss Katherine, but don't be afraid for yourself or Bobby. I think I can tell you how the evidence got in your room. I can answer nearly everything. There's one point—"

He broke off, glancing at his watch.

"Extraordinary courage!" he mused enigmatically. "I scarcely understand it."

Rawlins looked at him suspiciously.

"All this explaining may be a trick, Mr. Robinson. The man's slippery."

"I've had to be slippery to work under your noses," Paredes laughed. "By the way, Bobby, did you hear a woman crying about the time I opened this door?"

"Yes. It sounded like the voice we heard at the grave."

"I thought I heard it from the library," Robinson put in. "Then the rumpus up here started, and I forgot about it."

"The woman in black is very brave," Paredes mused. "We should have had a visit from her long before this."

"Do you know who she is?" Robinson asked. "And as Rawlins says, no tricks. We haven't let you go yet."

"I thought," Paredes mocked, "that you had identified the woman in black as Miss Katherine. She hasn't had anything to do with the mystery directly. Neither has Bobby. Neither have I."

"Then what the devil have you been doing here?" Robinson snapped.

"Seeing your job through," Paredes answered, "for Bobby's sake."

With a warm gratitude Bobby knew that Paredes had told the truth. Then he had told it in the library yesterday when they had caught him prowling in the private staircase. All along he had told it while they had tried to convict him of under-handed and unfriendly intentions.

"I saw," Paredes was saying, "that Howells wouldn't succeed, and it was obvious you and Rawlins would do worse, while Graham's blundering from the start left no hope. Somebody had to rescue Bobby."

"Then why did you give us the impression," Graham asked, "that you were not a friend?"

Paredes held up his hand.

"That's going rather far, Mr. Graham. Never once have I given such an impression. I have time after time stated the fact that I was here in Bobby's service. That has been the trouble with all of you. As most detectives do, you have denied facts, searching always for something more subtle. You have asked for impossibilities while you blustered that they couldn't exist. Still every one is prone to do that when he fancies himself in the presence of the supernatural. The facts of this case have been within your reach as well as mine. The motive has been an easy one to understand. Money! And you have consistently turned your back."

Robinson spread his hands.

"All right. Prove that I'm a fool and I'll acknowledge it."

Doctor Groom interrupted sharply.

"What was that?"

They bent forward, listening. Even with Paredes offering them a physical explanation they shrank from the keening that barely survived the heavy atmosphere of the old house.

"You see the woman in black isn't Miss Perrine," Paredes said.

He ran down the stairs. They followed, responding to an excited sense of imminence. Even in the private staircase the pounding that had followed the cry reached them with harsh reverberations. Its echoes filled the house as they dashed across the library and the dining room. In the hall they realized that it came from the front door. It had attained a feverish, a desperate insistence.

Paredes walked to the fireplace.

"Open the door," he directed Rawlins.

Rawlins stepped to the door, unlocked it, and flung it wide.

"The woman!" Katherine breathed.

A feminine figure, white with snow, stumbled in, as if she had stood braced against the door. Rawlins caught her and held her upright. The flakes whirled from the court in vicious pursuit. Bobby slammed the door shut.

"Maria!" he cried. "You were right, Hartley!"

Yet at first he could scarcely accept this pitiful creature as the brilliant and exotic dancer with whom he had dined the night of the first murder. As he stared at her, her features twisted. She burst into retching sobs. She staggered toward Paredes. As she went the snow melted from her hat and cloak. She became a black figure again. With an appearance of having been immersed in water she sank on the hearth, swaying back and forth, reaching blindly for Paredes's hand.

"Do what you please with me, Carlos," she whimpered with her slight accent from which all the music had fled. "I couldn't stand it another minute. I couldn't get to the station, and I—I wanted to know which—which—"

Paredes watched her curiously.

"Get Jenkins," he said softly to Rawlins.

He faced Maria again.

"I could have told you, I think, when you fought me away out there. No one wants to arrest you. Jenkins will verify my own knowledge."

"This is dangerous," the doctor rumbled. "This woman shouldn't wait here.
She should have dry clothing at once."

Maria shrank from him. For the first time her wet skirt exposed her feet, encased in torn stockings. The dancer wore no shoes, and Bobby guessed why she had been so elusive, why she had left so few traces.

"I won't go," she cried, "until he tells me."

Katherine got a cloak and threw it across the woman's shoulders. Maria looked up at her with a dumb gratitude. Then Rawlins came back with Jenkins. The butler was bent and haggard. His surrender to fear was more pronounced than it had been at the grave or when they had last seen him in the kitchen. He grasped a chair and, breathing heavily, looked from one to the other, moistening his lips.

Paredes faced the man, completely master of the situation. Through the old butler, it became clear, he would make his revelation and announce that simple fact they all had missed.

"It was Mr. Silas, of course, who came back?"

"Oh my God!" the butler moaned, "What do you mean?"

"I know everything, Jenkins," Paredes said evenly.

The butler collapsed against the chair. Paredes grasped his arm.

"Pull yourself together, man. They won't want you as more than an accessory."

Maria started to rise. She shrank back again, shivering close to the fire.

"Is your master hiding," Paredes asked, "or has he left the house?"

Jenkins's answer came through trembling lips.

"He's gone! Mr. Silas is gone! How did you find out? My God! How did you find out?"

"He said nothing to you?" Paredes asked.

Jenkins shook his head.

"Tell me how he was dressed."

The old servant covered his face.

"Mr. Silas stumbled through the kitchen," he answered hoarsely. "I tried to stop him, but he pushed me away and ran out." His voice rose. "I tell you he ran without a coat or a hat into the storm."

Paredes sighed.

"The Cedars's final tragedy, yet it was the most graceful exit he could have made."

Maria struggled to her feet. Her eyes were the eyes of a person without reason. That familiar, hysterical quality which they had heard before at a distance vibrated in her voice.

"Then he was the one! I wanted to kill him, I couldn't kill him because I never was sure."

"Did you see him go out an hour or so ago?" Paredes asked.

"I saw him," she cried feverishly, "run from the back of the house and down the path to the lake. I—I tried to catch him, but my feet were frozen, and the snow was slippery, and I couldn't find my shoes. But I called and he wouldn't stop. I had to know, because I wanted to kill him if it was Silas Blackburn. And I saw him run to the lake and splash in until the water was over his head."

She flung her clenched hands out. Her voice became a scream, shot with all her suffering, all her doubt, all her fury.

"You don't understand. He can't be punished. I tell you he's at the bottom of the lake with the man he murdered. And I can't pay him. I tried to go after him, but it—it was too cold."

She sank in one of the chairs, shaking and sobbing.

"Unless we want another tragedy," the doctor said, "this woman must be put to bed and taken care of. She has been terribly exposed. You've heard her. She's delirious."

"Not so delirious that she hasn't told the truth," Paredes said.

The doctor lifted her in his arms and with Rawlins's help carried her upstairs. Katherine went with them. Almost immediately the doctor and Rawlins hurried down.

"I have told Katherine what to do," Doctor Groom said. "The woman may be all right in the morning. What's she been up to here?"

"Then," Bobby cried, "there was a connection between the dinner party and the murders. But what about my coming here unconscious? What about my handkerchief?"

"I can see no answer yet," Graham said.

Paredes smiled.

"Not when you've had the answer to everything? I have shown you that
Silas Blackburn was the murderer. The fact stared you in the face.
Everything that has happened at the Cedars has pointed to his guilt."

"Except," the doctor said, "his own apparent murder which made his guilt seem impossible. And I'm not sure you're right now, for there is no other Blackburn he could have murdered, and Blackburns look alike. You wouldn't mistake another man for one of them."

"This house," Paredes smiled, "has all along been full of the presence of the other Blackburn. There has been evidence enough for you all to have known he was here."

He stretched himself in an easy chair. He lighted a cigarette and blew the smoke toward the ceiling.

"I shall tell you the simple facts, if only to save my skin from this blood-thirsty district attorney."

"Rub it in," Robinson grinned. "I'll take my medicine."

They gathered closer about the Panamanian. Jenkins sidled to the back of his chair.

"I don't see how you found it out," he muttered.

"I had only one advantage over you or the police, Graham," Paredes began, "and you were in a position to overcome that. Maria did telephone me the afternoon of that ghastly dinner. She asked me to get hold of Bobby. She was plainly anxious to keep him in New York that night, and, to be frank, I was glad enough to help her when you turned up, trying to impress us with your puritan watchfulness. Even you guessed that she had drugged Bobby. I suspected it when I saw him go to pieces in the cafe. He gave me the slip, as I told you, in the coat room when I was trying to get him home, so I went back and asked Maria what her idea was. She laughed in my face, denying everything. I, too, suspected the stranger, but I've convinced myself that he simply happened along by chance.

"Now here's the first significant point: Maria by drugging Bobby defeated her own purpose. He had been drinking more than the Band of Hope would approve of, and on top of that he got an overdose of a powerful drug. The doctor can tell you better than I of the likely effect of such a combination."

"What I told you in the court, Bobby," the doctor answered, "much the same symptoms as genuine aphasia. Your brain was unquestionably............