When did Matlock Styles last call on your father?"

"He called several times last week. I don't know exactly when he called last. But I do know that my father was greatly excited over something, and that he called in my stepmother and she was excited, too. I was not told what it was about."

"Well, to drop him, do you know a man named John Watkins, of Bryport?"

"Watkins? Yes, I do. He once called on my father, about the same time that Mr. Styles called last."

"Do you know why he called?"

"I do not. I thought it was about a patent. I learned that Mr.

Watkins worked for the United States government and I thought it was for the patent office."

"Then that is all, Miss Langmore." The detective arose and held out his hand. "Now take good care of yourself and do not worry. Matters are bound to come out right in the end."

"But how can they be better for me?" Margaret's face took on its worried look again. "They have proved that I am guilty."

"You are not guilty," said Adam Adams firmly and looking her squarely in the eyes. "You are not guilty. I say so, and I know. Do not worry. Rest quietly, and soon everything shall be made plain to you."

And then before she could answer he was gone. She sank back among the pillows, closed her eyes and heaved a sigh.

"It cannot be!" she murmured. "It is too late! I am guilty! I am guilty!"

CHAPTER XXII

AN UNDERGROUND MYSTERY

Late that afternoon a burly negro, plainly dressed and wearing a slouch hat, made his way along the river road in the direction of the old mill. He kept as much as possible in the shade of the bushes and trees and when close to the mill sank low in the tall gra.s.s, that he might not be seen by anyone who was pa.s.sing.

The negro was Adam Adams and his disguise was perfection itself. The detective was heavily armed and carried in his pockets several things which were unusual to him.

He waited around the old mill until the sun went down and the stars began to come out one by one. No one was in sight, but this did not ruffle him. He was ready to play a waiting game and take whatever was to come, even at the risk of his life.

Presently he heard a whistle at a distance. Then a man appeared whom he rightfully took to be the fellow called Bart. This individual pa.s.sed up and down the road near the mill and also came down to the water's edge, to gaze at the footpath on the other side of the river.

The man had the mastiff Queen with him and the dog came within a hundred feet of where Adam Adams was in hiding. Quickly the detective pulled a large atomizer from his pocket. Then, as the man walked back to the Styles' farmhouse, the dog turned and disappeared in the bushes as if following a trail.

"Don't come here, old lady," muttered the detective, as he stood on guard, with the atomizer ready for use. "If you do you'll be sorry."

The mastiff was following Adam Adams' trail and in a minute more she came up and set up a fierce growl. Then she made a savage leap forward.

The detective might have finished her with a shot from his pistol, for he was an expert marksman. But he had come prepared to strike a blow without making any noise. As the mastiff sprang at him, he held the atomizer at full length and let a portion of the contents fly full into the animal's face. There was a snarl and a gasp and the magnificent canine fell over on her side. Leaping forward, the detective held the atomizer at the dog's nostrils and used it vigorously for a few seconds. It was more than sufficient for his purpose and soon the animal stiffened out in death.

"It's a shame to kill so fine a brute, but it can't be helped," he muttered as he restored the atomizer to his pocket. He had used a mixture of chloroform, carbolic acid and other drugs, and the dog had been blinded as well as smothered by the application.

He left the mastiff where she had fallen and, as the darkness increased, drew closer to the mill. Then he saw a man approaching and recognized Matlock Styles. The Englishman entered the old mill, closing the door carefully behind him.

"More ghost work, I suppose," murmured the detective, but he was mistaken, no such manifestations occurring. Evidently they were to take place later.

Without making a sound he crawled up to a side door of the old mill.

It was unfastened, and pushing it open, he entered the lower floor of the building. All was silent.

He waited and after awhile heard a step overhead and a low murmur of voices. Then a man came down a narrow stairs, carrying a pole, a white sheet and a round, flat pan in which evidently something had been burnt.

"Looks like the ghost outfit," thought Adam Adams, as he crouched down behind some empty boxes and bins.

The fellow was tall, broad-shouldered and powerful looking, and Adam Adams felt certain he was not Matlock Styles. He wore a thin white bag over his head, with two holes for seeing purposes, and in one hand carried a flash lantern.

To the detective matters seemed to be growing tremendously interesting.

The man placed the things he carried in a closet partly filled with rubbish. Then he flashed his light around carefully. Adam Adams got down out of sight and placed his hand on the b.u.t.t of his pistol. He was resolved to take no more risks than were absolutely necessary.

Presently the light was lowered, and taking a peep Adam Adams saw the man kneeling down and tugging away at an iron ring in the floor. Soon a trapdoor came up, and the man, taking up his lantern, disappeared from view, closing the trapdoor behind him.

The detective waited for several minutes and then stole forward in the utter darkness. He had measured the distance perfectly and found the iron ring with ease. He pulled upon it gently but firmly and raised the secret door several inches.

A look below showed nothing but darkness. He strained his ears, and heard a faint noise at a distance but could not determine whether it was the flowing of the river over the stones or something else.

He got out his pistol and examined it with care, to make certain that it was ready for use. Then, with a quick motion, he threw up the trapdoor, dropped below, and closed the opening above him.

He felt as does a lion tamer stepping into a cage of beasts new to him.

He realized that he was on the verge of some important discovery, but that this investigation might cost him his life.

He was on a narrow staircase. There were but ten steps and then he found himself between two stone walls with the roof just above his head. Not caring to take another drop into the unknown, he advanced slowly, taking no step until he was sure of it.

Presently he came to a turn and then another. He could now see a light shining ahead, coming from under a heavy wooden door. The barrier was tightly closed. He tried it softly, to find it fastened on the other side.

There was a strange whirr and a clicking in the apartment beyond, as if some machinery was in motion. But then came a loud voice and the other sounds stopped. By getting down on his hands and knees Adam Adams was enabled to hear nearly all that was said in the place beyond the barred door.

"I will listen to reports," said a voice which sounded much like that of Matlock Styles. "Number One, have you performed the ghostly manifestations?"

"I have, chief," was the answer.

"Did you notice anything unusual?"

"A boy and a girl on the other side of the river ran away as if the Old Nick were after them."

"Anything else?"

"No, but it's Number Three's turn after tonight."

"Very well; Number Three, take notice of that. Number Two, there are but six of you here to-night. What of the other two?"

"A note was left at the foot of the tree. They could not come, for one had business in New York and the other business in New Haven."

"Very well. Number Three, what of the goods you shipped to Philadelphia day before yesterday?"

"I have a telegram that it was safely received and payment will be made to-morrow."