Mike Crotty was on deck. Eric readily found him.

The man was a stranger to him, but there is a mystic tie between the detectives and police in a great city—they work in harmony.

Soon the two men were conversing with the greatest freedom.

Crotty had often heard of Detective Darrell, and was only too glad to supply any information that lay in his power. He remembered meeting the hackman and spoke of the bells ringing out the midnight hour.

There could be no mistake.

When Eric left the officer, he was a badly puzzled man to be sure. Instead of having solved the mystery it was assuming even darker proportions, and the chances seemed equally divided.

Was Joe guilty or not?If, as these men agreed, he was at a certain place just as the solemn midnight hour rang out, how could he have been at the bal masque—it was at that hour of unmasking the Spanish bull fighter and his consort, the Lady of Cards, drove away in another vehicle and yet—that man possessed the stalwart figure of Joe Leslie—Eric believed he would know it anywhere—he had answered to the name of Joe, while his companion was Marian.

The difficulties in the way might have daunted a less persevering officer than Darrell.

They only spurred him on to renewed exertions. He gloried in a puzzle.

To a man of his nature it was the most pleasurable work in the world, studying the intricacies of a mystery, grasping a thread in the labyrinthine maze, following it along inch by inch, until the whole thing resolved itself into a solved problem.

Then, when the end came, how proud he would be to survey his work.

He began to give Joe the benefit of the doubt. This was one point gained.

It is a rule in American courts never to adjudge a man guilty until he has been proven so—the law looks upon him as innocent, and all efforts of the prosecutor are directed toward proving the charges.

In some other countries the opposite is the case and the accused has to prove his innocence.

Eric Darrell was gradually applying this former principle to the case in question.

Perhaps Joe might be innocent, and this cloud hanging over him be the result of circumstantial evidence.

At any rate the detective hoped so.

He looked at his watch mechanically.

Just now the thought came into his head that he must find out all about Joe before another night had spread its mantle over the city.

The time dragged along.

He had some work to do in his office, and this consumed something like an hour.

Then he made his way slowly in the direction of Twenty-seventh Street.

It was about four when he came in sight of the house around which clustered so much that was mysterious.

Sauntering along, he kept watch for Joe, feeling almost sure the other would come.

Sure enough, at the regular time his tall figure came in view.Darrell managed it so that at this moment he was nearly opposite the house.

He could see Joe without looking in a particular manner across the street, and he saw that the other appeared nervous and worried.

Was his guilty secret wearing on his mind?

Something undoubtedly disturbed him.

Any one could see that from the expression on his face.

As usual, when he came in front of the house, he turned and looked up the street, as though he were afraid lest some one whom he knew would recognize him.

Then he went up the steps.

There was no ringing the bell.

With a key he opened the door as though proprietor there.

Then Darrell, passing on, lost sight of him. The detective crossed the street beyond, and came on down, intending to pass the house again.

He changed his mind.

When just opposite, looking up he saw that fortune beckoned him.

The door was ajar.

Joe had been a trifle careless, and made a mistake when he thought he closed the door.What could be better?

Mr. Darrell was a man quick to make up his mind, and he instantly saw a chance here to further his plans.

Without hesitating an instant he advanced up the steps, stood upon the door-step, and seemed to glance around carelessly, when in reality he was listening to catch any sound that might come from the interior.

Another moment and he had entered.

Perhaps some one saw him, but he had put on an air of proprietorship such as Joe wore, and curious eyes must have simply reached the conclusion that his coming was but another link in the chain of mystery surrounding the house.

Once in the hall, the detective quietly closed the door, making sure it was fast.

Enough light came in through the glass above to show him the stairs.

There was carpet on the floor.

Near by were folding doors, and, as they stood ajar, Darrell poked his head through, not merely out of curiosity, but because he felt that he had an interest in the matter.

The parlor was furnished.

It was no empty house into which he had come thus surreptitiously.He listened.

Not a sound from within.

How strange it seemed.

What could it all mean?

Vague and even terrible ideas flashed into his mind—was Joe connected with some secret cabal or society that met here every day?

Perhaps some awful secret was gnawing at his vitals, and daily sapping his life.

What was that?

A door slammed above.

Eric was glad to hear it, for he realized that the house had something human about it.

As near as he could judge the sound came from upstairs.

Then he would not have to grapple with the demons of the underground world.

At times even the oddest fancies will surge through the most prosaic mind.

One of the thoughts that had come to him was that possibly Joe had become connected with some gang of counterfeiters—he had heard of things just as strange—and although it seemed a preposterous idea in connection with Joe, still it had already become apparent that there was something very strange connected with him and why not this as well as any other?Lately Eric had been reading Doctor Jekyll and Mr. Hyde, and his mind was full of strange fancies concerning the awful change that was wont to come over that unfortunate being, who lived two lives, each unknown to the other.

It did not seem possible that Joe Leslie could be doing this exactly, but he might be carrying on two characters successfully.

At his business and his home up-town he was known as Joseph G. Leslie—on Twenty-seventh Street he might be Mr. Lester. To tear the mask away and expose the truth was what brought the detective here now.

In the interest of justice he was bound to do this much.

Then again he thought of Lillian.

In his indignation he wished she could be there to face her husband when his guilty secret was laid bare.

It might seem cruel—so does the hot iron of the doctor when applied to the marks left by the teeth of an enraged dog, but it is done with kindness—heroic treatment saves one from something more terrible beyond. Perhaps, if faced by Lillian, Joe would break down and receive a shock that would last him all the rest of his natural life.So the detective made up his mind not to betray his presence now if he could help it, but reserve the denouement to a later date, when it could be made more dramatic.

All he meant to do now was to secure certain evidence for future use.

The stairs, being carpeted, gave forth no sound when he began ascending.

He felt rather peculiar about this whole business—had this man been a stranger he would not have experienced this same uneasiness; but Joe Leslie—to think that he should be upon the track of his old friend, and with such a purpose in view.

Once the stairs creaked under his weight and he stood still—the sound was preternaturally loud in an empty house; but there was no result, so that he presently continued his course of exploration.

Vehicles rumbled past the house—he could hear them plainly, as though some window were open near at hand.

Just as he reached the top of the stairs a cough reached his ears—it was a man who gave utterance to it, probably Joe.

No voices?How singular!

Eric Darrell’s wonder arose with each passing moment—strange to say, he was trembling all over now with excitement.

No living soul had ever seen this man in such a condition before, which fact went to prove how deep his interest was in the game he was now pursuing.

Not for worlds would he have stopped, now that his hand was on the plow.

The end must be near, and Joe’s deep secret could not long remain such—it must be met and dragged to the light.

Darrell looked around him, since he was now at the head of the stairs.

The house seemed to be furnished throughout, and yet there seemed an air of desertion and loneliness about it, as though it lacked the daily care of a housekeeper—little things seemed to be lacking that would indicate the fact of its being a habitation that was occupied—where human beings lived and moved.

Somehow this fact impressed itself on the detective’s mind.

He did not have much time for thought, as action was necessary.When the brave soldier finds himself face to face with the enemy, he does not spend the minutes in reflection, but acts.

So with Eric—he had looked forward to this period for quite a time, and now that it had arrived, he was not the one to tarry.

Where was Joe?

As nearly as he could place them the sounds had come from the front room.

He crept silently along in that direction—the door was open, and nothing prevented his seeing the interior of the apartment.

It was furnished, but did not contain a single occupant—light crept through the inside blinds, sufficient to show him this fact, and his wonder was simply increased to a fever heat.

In the name of heaven, what did all this strange mystery mean—where was Joe—what freak induced him to come here, and—

An odd, crackling sound reached his ears—ah! it proceeded from a small room used as a dressing-room, the door of which was closed.

Eric crept over to it and listened—all was as still as death within.

Baffled in this endeavor, he leaned against the door, pressing his ear close to the panel, to catch any voices—if conspirators were gathered there they must talk—this silence could not be long maintained.

The door must have been on the latch—at any rate it was not fastened, and as Eric leaned against it this impediment to his vision slowly gave way, opening a foot or so, and Joe Leslie’s terrible secret was revealed to the detective’s eyes.