ted to listen. There was a dead silence. The man had realised that
he was being followed, and had plunged into the forest.

So, disappointed, I was compelled to retrace my steps to the hotel.

I tried to telephone to Ray, but was told that late the previous night
he had gone out on the car and had not returned.

Therefore I remained there, impatient and helpless, the mysterious Smith
being still absent.

At three o'clock that afternoon the car pulled up before the door and
Ray descended.

"Put on your coat and come with me," he said briefly. And a few minutes
later we were tearing along over the same road which the mysterious
Smith had taken in the darkness--the direct road which leads north by
way of Dava, away to Forres.

Just past the little school house of Dava we left the main road, and
striking across the wide, bleak, snow-covered moor for about a mile,
suddenly came into view of a wide and lonely expanse of dark water in
the centre of the desolate landscape. It was Lochindorb, where, in the
distance, we had seen the Kershaw aeroplane alight and sail along the
surface.

As we reached the edge of the loch I saw out upon a small islet in the
centre a ruined castle, a long, almost unbroken, grey wall of uniform
height, without turrets or battlements, occupying the whole of the
islet. Below the walls a few bushes grew from the water's edge, but it
was as dreary and isolated a spot as I had ever seen. Beyond stretched
the big, dull sheet of water, backed only by the low, uninteresting
moorland, the only break in the all-pervading flatness and monotony
being afforded by a few wind-stunted trees on the right of the road, and
a small dark plantation ahead.

When the car had stopped and we had got out and walked a few yards, Ray
said:

"Yonder is the old castle of Lochindorb, Jack. Behind those walls is the
shed which shelters the Kershaw aeroplane. Look!"

And gazing in the direction he indicated, I saw a skiff with three
occupants coming across from the shadows on the left towards the island.
The man steering was a corporal of engineers in khaki.

"It appears," Ray went on, "that the machine takes her flight from the
open surface of the loch, which, as you see, is about two miles long.
She enters and leaves the shed by water."

As we were speaking, a bearded gillie of gigantic stature came up from
nowhere and promptly ordered us away, an order which we were very
reluctantly compelled to obey.

At last, h