ough he searched the room with painstaking care, he found nothing.

It was while he was thus engaged that a faint rustle aroused his
attention, and looking towards the corner of the room whence it
proceeded, he saw a large rat crouching by the skirting-board watching
him with malevolent eyes. Colwyn looked round for a weapon with which to
hit it. The creature seemed to divine his intentions, for it scuttled
squeaking across the room, and disappeared behind the wardrobe.

Colwyn approached the wardrobe and pushed it back. As he did so, he had
a curious sensation which he could hardly define. It was as though an
unseen presence had entered the room, and was silently watching him. His
actions seemed not of his own volition; it was as though some force
stronger than himself was urging him on. And, withal, he had the uncanny
feeling that the whole incident of the rat and the wardrobe, and his
share in it, was merely a repetition of something which had happened in
the room before.

The wardrobe moved much more easily than he had expected, considering
its weight and size. There was no rat behind it, but a hole under the
skirting showed where the animal had made its escape. But it was the
space where the wardrobe had stood that claimed Colwyn's attention. The
reason why it had been placed in its previous position was made plain.
The damp had penetrated the wall on that side, and had so rotted the
wall paper that a large portion of it had fallen away.

In the bare portion of the wall thus revealed, about two feet square,
was a wooden trap door, fastened by a button. Colwyn unfastened the
button, and opened the door. A black hole gaped at him.

The light of the candle showed that the wall was hollow, and the trap
opened into the hollow space. There was nothing unusual in such a door
in an old house; Colwyn had seen similar doors in other houses built
with the old-fashioned thick walls. It was the primitive ventilation of
a past generation; the doors, when opened, permitted a free current of
air to percolate through the building, and get to the foundations. But a
further examination of the hole revealed something which Colwyn had
never seen before--a corresponding door on the other side of the wall.
The other door opened into the bedroom which had been occupied by Mr.
Glenthorpe. Colwyn pushed it with his hand, but it did not yield. It was
doubtless fastened with a button on the outside, like the other.

Colwyn, scrutinising