A few feet to the right of their doorway the palace wall ran out into the garden at a right angle for about fifty feet, thence it again turned off at a right angle to the right. The garden ran around this extension and back into a recess on the other side like the lower part of a large letter L.
Suddenly a woman’s stifled scream tore the silence apart. It ceased abruptly, suggestive of the clapping of a hand over the mouth of the one who had screamed. The sound seemed to come from the recess at the far side of the garden.
In a dozen lithe bounds Robert had rounded the wing of the palace, and was in sight of the far end of the garden. He fancied that he caught a fleeting glimpse of some light, loose garment in the dark shadows of the recess. A faint sound as of the stealthy turning of a lock followed and all was again quiet.
A moment later Professor Palmer joined him.
“What’s up?” he asked huskily, puffing from his exertion of attempting to keep pace with Robert.
“Don’t know. Imagined I saw a woman’s garment fluttering a moment ago. Suppose we have a look over there in that black corner.”
A solitary dark window looked out sinisterly from the recess. Robert had an uncomfortable feeling that they were being watched from it as they approached.
As they drew close to the wall where it joined the building Robert caught sight of something they had failed to notice before in the darkness. This was a massive, closed door in the corner of the wall.
“The door I heard locked a minute ago,” whispered Robert.
He put his shoulder to it, but failed to move it.