He sank his head upon the table and sobbed at the thought of his own impotence.
What was that?
In the silence he heard a gentle scratching sound--low, but very distinct in the quiet of the night.

It came from the door of the house.

Ferrier crept into the hall and listened intently.

There was a pause for a few moments, and then the low insidious sound was repeated.

Someone was evidently tapping very gently upon one of the panels of the door.