Sometimes their footsteps fell on the rock, awaking strange echoes down the gallery.

Sometimes they sank deep into the sand.

Cecil looked often behind, and once held out his hand to help his companion over a difficult place.

At last he paused, and she heard him struggling to turn a key in a great worm-eaten door on their right.
"This is the room," he explained, "where they held their meetings, and where the stuff was hidden.

It was used for more than twenty years, and the Customs' people never seemed to have had even an inkling of its existence." He pushed the door open with difficulty.