At last they turned suddenly out of the road, into the grounds of a private house.

The sound of the wheels was evidently heard within, and the front door was thrown open, letting out considerable light from the hall.

Nick could not go too near that light, so he let go, and crept into some shrubbery.

The carriage drew up before the door, and the colonel and his companion hurried into the house, leaving the horse tied.

The detective failed to obtain a good view of the woman or of the person who had opened the door.  The latter seemed to be a servant.

When the door had closed, Nick crept up.

He manoeuvred carefully, and discovered that there was somebody sitting in the hall just inside the door.

Entrance by that means was out of the question.

However, he succeeded without much difficulty in entering the house from the rear.

He found himself in the kitchen, from which he passed to a dining-room.

This apartment was almost totally dark.  Nick felt his way to the side opposite the kitchen, and came to a heavy pair of folding doors.

From the other side came a confused murmur of voices, as if many persons were talking in hushed tones.

Presently they became quite still and then there arose the sound of music.  It was a slow and somber strain, as from an organ gently played.

Nick was crouching against the door, among the folds of a curtain which could be drawn across.

Suddenly he heard a slight sound behind him.  He turned noiselessly.

A white figure flitted across the room.

Nick was at one end of the folding doors, and the figure passed to the other end and into the corner beyond.

There it suddenly vanished.

The light was so dim that Nick could not tell exactly what had happened.

It certainly seemed as if the figure had gone straight through the wall.

About a minute later another form appeared in the same way.  It crossed the room, and vanished.

“Good!” muttered Nick.  “I’ll back these ghosts against any that Colonel Richmond can raise in his house.”

Almost immediately there was the sound of a voice in the room beyond the doors.

“Does any person present recognize a departed friend?” it said.

Then Colonel Richmond’s voice arose, hoarse and trembling with emotion.

“Aunt Lavina,” he said, “tell me what you wish me to do.  I will obey you absolutely.”

“I thought so,” chuckled the detective.  “The colonel has come to attend a spiritualistic seance.”

CHAPTER VI.

A round-up of spook-artists.

It began to look very much as if Horace Richmond’s theory was correct.  Certainly the colonel had fallen again into the clutches of bogus mediums.