A little way down this lane, between the trees, the silhouette of a gabled house loomed blackly against the star-powdered sky, and it was in an upper window of this house that the Saint had seen the light as he passed. Now he skilfully lighted a cigarette with one hand, and stared down the lane. The light was still there. The Saint contemplated it in silence, immobile as a watching Indian, till a fair, sleepy head roused on his shoulder.
"What is it?" asked Patricia.
"That's what I'd like to know," answered the Saint, and pointed with the glowing end of his cigarette.
The blinds were drawn over that upper window, but the light could be clearly seen behind them—a light of astounding brilliance, a blindingly white light that came and went in regular, rhythmic flashes like intermittent flickers of lightning.
The night was as still as a dream, and at that moment there was no other traffic on that stretch of road. The Saint reached forward and switched off the engine of the Furillac. Then he listened—and the Saint had ears of abnormal sensitiveness— in a quiet so unbroken that he could hear the rustle of the girl's sleeve as she moved her arm.
But the quiet was not silence—it was simply the absence of any isolated noise. There was sound—a sound so faint and soothing that it was no more than a neutral background to a silence. It might have been a soft humming, but it was so soft that it might have been no more than a dim vibration carried on the air.
"A dynamo," said the Saint; and as he spoke he opened the door of the car and stepped out into the road.
Patricia caught his hand.
"Where are you going, Saint?"
Simon's teeth showed white in the Saintly smile.
"I'm going to investigate. A perfectly ordinary citizen might be running a dynamo to manufacture his own electric light— although this dynamo sounds a lot heavier than the breed you usually find in home power plants. But I'm sure no perfectly ordinary citizen uses his dynamo to make electric sparks that size to amuse the children. Life has been rather tame lately, and one never knows. . . ."