Mr. Shelton spoke truly when he said to Mr. Lawrence that he would shadow Harold Colville like a bloodhound.

By day and by night, on foot or on horseback, in various disguises, he kept himself on the track of the fine gentleman.

For several weeks he kept up this close espionage, but at the end of that time he seemed no nearer his object than when it was first begun.

Mr. Colville's comings and goings seemed to be quite the same with those of other gentlemen of his means and position.

He frequented theaters and gaming-houses; he was a welcome and much sought-for partner in ball-rooms, and was smiled upon by scheming mothers with marriageable daughters.

Thus far Mr. Shelton had seen nothing on which to seize as a possible clew to Mr. Colville's mysterious presence in Mr. Lawrence's house the night of Lily's appearance.

Mr. Shelton had made one discovery, however, though he did not begin to attach much importance to it. It was that Doctor Pratt and Harold Colville were acquainted with each other, and, moreover, that they sometimes "hunted in couples."

That is to say, the worthy physician occasionally stopped his carriage on meeting Colville, whereupon the latter would spring in and accompany the doctor on his round of visits, seeming deeply interested in the conversation they pursued together.

Mr. Shelton was puzzled to decide whether there was any collusion between the gay man of fashion and the busy physician, or whether it was only one of those odd friendships that are sometimes observed to exist between persons of totally different temperaments and pursuits. Sometimes he was inclined to believe it was only the latter.

But he noticed a fact at last that struck him as rather peculiar. Following the pair closely on his stout, black horse, he had seen that Colville always remained in the carriage while the physician went into the houses to pay his visits to the sick.

On this occasion, which struck him so forcibly, they drove quite out upon the outskirts of the city, and stopped before a house standing almost a half mile distant from any other.

This house, the detective observed, had a gloomy and forbidding aspect, being closely shuttered and surrounded by a very high stone wall.

Here Dr. Pratt descended and fastened his horse. Mr. Colville also sprang out, and they entered with a familiar air, the heavy gate closing and shutting them in.

"Now, that is rather strange," thought the detective as he walked his horse slowly past the deserted-looking place.

"What business has Colville in there? I can imagine that Pratt may have a patient inside those gloomy walls; but what the deuce can Colville have to do with it? I am almost positive that I heard shrieks issuing thence when they went in at the gate. I wonder can it be a private asylum for the insane?"

He spurred his horse ahead and rode on for some distance, then paused, and remained as erect and still as a statue while he watched and waited for the pair of confederates to come forth. But at least an hour elapsed before they emerged, and pursued the devious tenor of their guilty way.

"Now, upon my word," thought the wary spy, "Doctor Pratt must have a very interesting case inside of those gloomy, prison-like walls. I have a mind to stop somewhere in the neighborhood and inquire about the inhabitants thereof."

He accordingly suffered Doctor Pratt's carriage to drive on out of sight, and stopping before a cottage on the road with the ostensible purpose of obtaining a drink of water, he inquired of the woman who gave it to him as to the names of the people who inhabited the old house with the stone wall.

"And indade, it's mesilf that cannot tell ye, sor," said she, with a very broad Hibernian accent, "for shure, Mickey and mesilf have but lately moved intil the cot, and knows naught about the nayburs!"

Mr. Shelton rode on and made the same inquiry at the next house, but elicited no encouraging answer. People did not seem to know anything about the deserted-looking old house in such close proximity to them.

After several similar experiences he rode on quite disgusted with the general stupidity of the neighborhood.

Almost two miles from the old house that had so powerfully attracted his interest, he came upon a little house standing close to the roadside.

A kind-looking woman sat in the doorway, though the day was chilly, and as she kept knitting away on the homely gray stocking, sang cheerily at her work.

"Now that is a pleasant-looking old soul," he thought. "Perhaps her intellect is above the average of her neighbors. Perhaps she is better informed than they are. At any rate, I will speak to her."

He dismounted from his horse this time, fastened him at the gate-post, and walked up the narrow path to the door.

The good woman arose in quite a flutter.

"Do not let me disturb you," said he, courteously. "I only wish to trouble you for a drink of water. I have ridden far and feel very thirsty."

"Certainly, sir," said the woman, in a voice as pleasant as her face. "Come in and have a seat, sir, and you shall have a draught fresh from the spring."

She hurried away on hospitable thoughts intent, and soon returned with a glass of pure cold water. The guest sat still in his homely chair and sipped at the water very slowly considering how thirsty he had professed himself to be.

The fact was, he had drank several glasses of water already while prosecuting his inquiries, and began to feel himself almost unequal to this latter one.

"You do well to sip your water slowly, sir," said the woman, observing him, "for the doctors do say that it is very imprudent to drink rapidly when tired and overheated."

"Bless the good, unsuspecting soul," thought the detective. Aloud he said very politely: "Yes, madam, I am aware of that fact, and I believe some very severe illnesses have resulted from injudicious gulping down of cold water by thoughtless persons. I always make a point of sipping mine very slowly."

"And very right of you, too, sir," said the kind soul, approvingly.

"Ah, by the way," said he, "I am a stranger in this neighborhood, and I passed a house about two miles back that powerfully attracted my curiosity. It was an old, deserted-looking building, inclosed by a high stone wall. Its prison-like aspect repelled me. Do you know anything about it?"

"They do say it was a convent once, sir," answered the good woman, readily. "I know the place you speak of, and as you say, sir, it has a very repelling aspect."

"Is it inhabited now?" inquired the wayfarer.

The hearer shuddered.

"That it is, sir," said she; "and by a wicked lot, I assure you."

"Is it possible?"

"It is quite true, sir. The place has been inhabited for many years by an old couple of the name of Leveret. They have no family at all, and live there alone, having no friends or neighbors, and it is said that they keep a powerful bloodhound upon the place. Strange tales are told of these people, but nothing is known certainly. Both of them are hideously ugly, and many people declare that the old woman is a witch."

"Is either of them sick, do you know?" inquired the detective.

"That I cannot tell you, sir. They are all very reserved, and hold no intercourse with people around them. I have heard that they are misers, and have large quantities of gold buried in their garden, and guarded by the great bloodhound. They might both sicken and die, and not a living soul be the wiser. May I inquire why you asked that question, sir?" asked she.

"Certainly. I saw a doctor's carriage standing in front of the gate, and concluded that someone must be sick, within."

"Perhaps there may be, sir, but I would not have thought they would have called in a doctor. These old witches, like Haidee Leveret, as they say her name is, usually cure sickness with their own herbs and simples."

"Perhaps they failed on this occasion. Well, I must be going," said the detective. "Many thanks for your information. Permit me to offer you a trifle for your kind entertainment," said he, politely tendering a piece of silver.

"Not a penny, sir. The water costs nothing, and as for changing a bit word with you, why, that's a pleasure to a lonesome old lady like me, with few neighbors and friends. Why, it was only last month that a young thing in trouble, passing this way, offered me her fine diamond ring to pay for a bit kindness I showed her. But I refused it, sir. I want nothing for showing a little kindness to the wayfaring," said the good woman, pausing to take breath.

Shelton's attention had been caught unaccountably by the mention of the diamond ring.

"You stimulate my curiosity," said he, deliberately sitting down again. "The young person must have felt your kindness very sensibly to have offered such a costly reward as a diamond ring."

"Aye, she was in sore trouble, sir, that I believe. But now I bethink me," said the good creature, stopping short, "she charged me if any one came here inquiring for her to say she had not been here, and here I am blabbing away at this thoughtless rate."

"But you see I am not inquiring for her," said the visitor briskly. "I am a perfect stranger in these parts, and I am not looking for anyone, so there is no harm done in relating this interesting story to me."

"Why, that is very true, sir," said she, and thereupon followed a minute and detailed account of the visit of Lily Lawrence, and the disguise she had furnished her. Mr. Shelton listened to the story with very close attention.

"How long ago has it been since this happened?" he inquired when she had finished her relation.

"Several weeks, sir. Stay, let me see—I was so excited by it that I put down the date in my little memorandum book," she said, as she began to fumble in her pocket. Presently she produced the book in question, and turning a leaf announced triumphantly, "it was fully two months ago, sir. It was August—the 21st of August."

"The very day that Lily Lawrence appeared to her friends," thought the detective, with a start. "Can there be any connection between the two?"

"She was young and beautiful, you say?" asked he.

"Aye, she was, sir. Not more than seventeen or eighteen, and beautiful as a white lily, sir. She put me in mind of that flower, she was so delicate and pale, sir—not a tint of color in her poor lips and cheeks. Her hair was pale golden too, sir, falling down upon her shoulders, and her eyes of a beautiful deep blue."

"I suppose no one came by to inquire for her?" said Shelton.

"No one, sir; I did not see anyone passing that day except a doctor's carriage that whirled past in a desperate hurry soon after she left here."

"Let us hope she made her escape from whatever evils menaced her," said he, fervently. "Well, I must be going in earnest now. My kind friend, will you tell me your name? I may call on you again."

"My name is Mrs. Mason, sir," she answered.

"Do you live here alone?" asked he, as he jotted it hastily down in his note-book.

"Quite alone, sir. My poor husband and my only child have been dead these ten years—I am quite alone in the world," answered Mrs. Mason with a sigh.

"Good day, Mrs. Mason, and many thanks for your kindness to a wayfaring man," said the detective as he went down the path, leaped into the saddle and rode away.

Mrs. Mason's revelation had thrown his mind into a chaos of doubt, perplexity and suspicion. New light began to break in on him, startling him with a wondrous possibility he had not suspected.