At McKelvie's request I parked my car a block from the house and we traversed that distance in silence, entering the grounds as though we had come on no good errand. When we reached the house McKelvie piloted me to the back and rang the servants' bell. It was late, after six, and growing dark so that Mason was hardly to be blamed if he failed to recognize us, especially as he did not expect to see us again so soon.

"It's Mr. Davies, Mason," said McKelvie. "Will you let us in to the main wing through the passageway, please?"

"Yes, sir," returned Mason. "This way, sir, if you please."

He led us through the passageway and opened the door into the main wing, going ahead of us to switch on the light in the hall.

"That is all. Leave the door open into the passageway. We shall probably depart the way we entered."

"Very good, sir."

McKelvie waited until the old man had shuffled away before he approached the study door. It was little more than six hours since we had been in that room, yet it seemed more like a week to me, so many things had cropped up in the interval, and I waited impatiently for McKelvie to turn the knob of the door.

"I thought I heard someone in there," he whispered, and flung open the door.

For one swift instant I had the impression of a glaring eye that winked and faded as I looked, then only darkness confronted us, darkness and a brooding stillness in which I could hear my very heart-beats.

McKelvie stepped into the room and found the switch, then as the study was flooded with light, he turned and sped toward the safe with me at his heels.

"The windows," he said tersely, as he spun the dial. "See if anyone is hiding behind those curtains."

I hurried to the windows and swept back the hangings. There was no one there, and I turned back to the safe just as McKelvie stood up and swung open the door.

"Come on," he said, thrusting his skeleton key into the inner door. "Don't forget to stoop and be careful to make no noise."

I followed him as he lighted his flash, and passed quickly through the secret room to the door at the head of the stairs. Unlocking this he motioned me to keep near him, and together we crept down the stone staircase and out into the night. We listened a moment, but the only thing we heard was the wind in the trees, which seemed to mock us shrilly as we peered into the dusk beyond.

"Come on back," said McKelvie quietly. "We have work to do yonder," and he nodded toward the entrance.

Wonderingly I obeyed him but asked no questions as he relocked the door and led the way back to the secret room. Here he paused to turn on the light and then lifting the divan aside with my help, he knelt and felt the wall against which it had been placed.

"What is it?" I whispered. His haste and mysterious actions made me feel somehow that to speak aloud would be to commit an unpardonable offense.

He raised his head as though listening to sounds from without, then he sprang to his feet.

"The divan, quick, and no noise," he whispered.

I stooped to help him and as we lifted the divan to its place the fringe of the cover caught in my cuff-link. I tried to untangle it, but McKelvie had no time for such niceties. He wrenched the fringe free, leaving a strand in my link, and as he did so something fell to the floor and rolled along the carpet. He pounced upon the object, then suddenly turned and switched off the light. By the aid of his flash he crept to the rear door, and I distinctly heard the sound of steps on those stairs as McKelvie unlocked the door.

With a sudden movement he pulled the door open and flashed his light on the stairs. Again there was nothing but darkness and brooding stillness, and I could see that the door at the bottom was tightly closed.

"Well, I'll be hanged," muttered McKelvie. "I must be hearing things. Let's get back to the study."

We returned to the brightly lighted room and McKelvie locked up behind him with scrupulous care. Then he went over to the table and seated himself at its head in the chair in which Darwin had been found, and motioned me to take the place beside him.

"Funny thing," he said presently. "I could have sworn there was someone in this room when we first entered. I'm positive I saw this lamp go out."

"Was that it?" I answered. "It looked like an eye to me, a great glaring eye that faded as I gazed."

"You saw it too, then? I'm glad of that," he returned. "I was beginning to think I was the victim of hallucination. No, it was the lamp, which means someone was in that safe. However, he had the start of us, and there is not much use in trying to catch him at present."

"Who was it?" I asked eagerly. "Do you suspect?"

He made no answer but took from his pocket the object which had fallen from the divan. It was a heavy gold ring, evidently a man's. He looked at it critically and then held it out to me.

"Do you know whose it is?" he asked low.

Before I could take it from him he hastily slipped it back into his pocket and leaning closer, said in my ear, "Don't make a sound, but look at the safe door. Then turn back and listen to me as though nothing were amiss."

I was sitting around the corner from the head of the table with my chair turned slightly in McKelvie's direction so that my back was partly toward the safe. At his words I turned and looked at the safe door, expecting I know not what, and to my amazement I saw that the knob of the dial was turning silently and apparently of itself!

There was only one explanation. Someone was opening the door of the safe from the inside, somebody who knew the combination which McKelvie had used! And yet how could anyone have cognizance of the six letters McKelvie had picked out to close the safe. For this was no attempt such as Jenkins had made, no adept manipulation, since the dial was turning with precision, as though the hand that twirled it knew exactly how to spin it.

McKelvie's foot on mine recalled the remainder of his injunction, and turning back, I held out my hand for the ring. His lips formed the word, "No," and his eyes directed me to what he held in his hand. It was Lee Darwin's stick-pin.

"I thought there was someone in the room when we entered," he said in a clear voice, "but since you say you did not see the light, why I must have been mistaken. The case is getting on my nerves, and nerves are queer things when they begin to jump. I've been working too hard, and it's time I took a vacation."

He paused, and I had an uncomfortable feeling that whoever was in the safe had succeeded in opening it and was gazing at us from behind the shelter of the door. I shuddered as I realized the intensity of those unseen eyes which held me riveted to my chair. I longed to turn around and look and so break the spell, but McKelvie's glance on mine forbade it.

"I'm convinced that Lee killed his uncle," he continued. "The stick-pin proves his presence, and doubtless he had knowledge of the entrance. There is nothing more to be learned from this study. My work from now on must be conducted outside. As I said, I've got a man in the South and until he picks up Lee's trail there is nothing more to be done."

He stood up and put the pin away. "I'm dog tired. We've had a strenuous day. Take me home, Mr. Davies. I've earned a few days' rest."

Disappointedly I looked up at him. He spoke very convincingly and he did look tired, but somehow I had hoped that the ring had opened up a new line of inquiry for the morrow. Inaction was hateful to me while Ruth remained a prisoner. I wanted to be up and doing, even if it was only following a false scent.

"Come on, Mr. Davies. It's long past dinner time," he said impatiently.

"All right," I said reluctantly, rising and glancing casually at the safe as I did so. To my surprise the door was closed and had the appearance of never having been touched. Was I too beginning to have hallucinations?

A warning pressure as McKelvie took my arm made me mask whatever astonishment I felt, and also made me hasten with him from the room without a backward glance. When we were in the hall I opened my mouth to question him, but he shook his head and hurried me along to the door leading into the servants' wing.

"Wait here a moment," he said, indicating the passageway. "I'll be back in a second. Keep the door closed."

He disappeared down a side hall and I stepped into the passageway and closed the door, wondering what it was all about, and particularly who the man was who had evaded us to-night, if it was a man and not a freak of my imagination. Still, McKelvie had heard him, too, and it was hardly likely that both of us were dreaming.

"Come, we'll have to hurry," said McKelvie, returning suddenly.

In silence we let ourselves out the back door and crept through the grounds to the gate. In another minute we had gained the corner and my car.

As I drove toward town I remarked, "Was there really someone in that safe, McKelvie?"

"Certainly. I thought I was mistaken at first, but he came back again, as you observed. I thought you looked uneasy while I was talking," he said laughing.

I reddened. "It wasn't very pleasant to feel his eyes on me and be forbidden to see who it was. You were facing the safe. You saw him?" I questioned.

"No, I didn't see him. He was too clever to risk that. He knew we were there, and he came to find out how much progress we had made toward putting him behind the bars where he belongs," retorted McKelvie grimly.

"You don't mean to tell me that it was the criminal himself who had the nerve to come there to-night?" I said.

"It must have been, for who else has a key to those doors? Remember that he took Darwin's key, and mine is the only other one that will open those locks. Also he would be too clever to take anyone else into his confidence," he replied.

"How did he know the combination that you used?" I continued.

McKelvie laughed. "When I locked the safe the other day I used the word, Darwin, the one you suggested. He has since made himself acquainted with that combination. Just as he was too clever to change it so that I would believe the safe untampered with, so was I too clever to let him know that I suspected his visits."

I nodded. "Why didn't you go over to the safe and capture him then?" I asked. "You missed an opportunity."

"What happened when we chased him before? The moment he saw us making for the safe he would be gone. Besides, I was playing a little game. I had put him on his guard by hunting for him. I decided to trick him into thinking that I no longer had any interest in him."

"Then all that very convincing conversation——"

"Was mere bunk," he answered. "I'm glad it was convincing, though, for I was trying to fool a very clever devil."

He fished around in his pocket and drew out the ring. I could see it gleam in the light of the street lamps as we sped toward the park.

"Strange. I had an idea that there was a secret panel or something of the sort where he could hide such things as he needed, for I could figure no other reason for his coming to that house, and that is what I was hunting for when you so opportunely caught your cuff-link in that Persian cover. This ring must have been tangled in the fringe and when I yanked the cover I dislodged the ring. That was a stroke of pure luck, and it changes the whole course of the inquiry. Word from Chicago would have told me something, but not as much as this band of gold does. Take a good look at it and tell me whose it is."

He took out his flash and played it over the ring while I looked at it. Then I turned away, feeling sick at heart. The ring was a heavy gold signet with a deep-cut monogram, and it was a ring I knew only too well, since I had bought it myself at Ruth's request that she might give it to her brother on his birthday. That was three years ago, and what a very happy time it had been and how pleased Dick had seemed to receive the ring, for he always made a fuss over Ruth. I remember that he swore to wear it always as he slipped it on his finger, and now here it was cropping up to bring more misery to the girl I wanted most to shield from all harm and sorrow.

"Well?" McKelvie's voice broke the thread of my thought.

"It's Dick Trenton's," I said low. "And now shall I drive you home?"

"Home? I should say not!" he almost shouted. "We're going to get some dinner and then we're off to Water Street. The trail's too hot to turn aside now."