“Yes; we will come to-morrow,” Galabin said. “Although, after all, there may be nothing worth troubling to see. But I must confess——”
He stopped as Von Tressen knocked his arm sharply. An extraordinary thing had happened. For the moon coming out in its full brightness showed the wall blank now, without a trace of the window whence the light had shone.
At first neither man could realize it nor believe his eyes. Then, as they became certain of the strange disappearance they looked at each other in amazement.
“Where has the window gone to?” Von Tressen exclaimed, with a short laugh.
Galabin shook his head. “Rather mysterious, is it not? Let us cross over again and make sure that it is not an optical delusion.”
In a few seconds they were under the wall, looking in vain for a sign of the window.
“It was directly above us here,” Von Tressen said. “I would swear to that. I marked it by the triangular flower-bed. But where is it now?”
The dark wall above them presented an unbroken surface of stone. The moon shone out for a moment and proved it clearly. There was no window.
“Well,” observed Galabin, as they turned away from their puzzled search, “at least we have found something mysteriously interesting to follow up. Count Zarka is evidently a man worth the trouble of watching. We will come again to-morrow night, and may have better luck.”
So without seeing anything further to excite their curiosity they returned through the forest to their camping-ground.