“What’s that?” queried John. “Do you hear it?”
Both boys listened, but Stan heard nothing save the water lapping the edges of the cove, which was about a quarter of a mile across, the sound carrying clearly on the night breeze which curved down over the bowl of hills and dipped cat’s-paws at the dark water. The same breeze made the trees sigh a little, and outside of that there was no other noise.
“I thought I heard a familiar sound, at least a sound I’ve heard before, like—look!”
The boys saw a shimmer of broken water as they turned about, attracted by a low humming!
“A boat, Stan, and crossing the cove at good speed, too! See, there he goes!”
A single blink of light came from the flashlight on the hill and Stan saw an answering blink from the boat. Then darkness enveloped all again and the hum was heard no more!
“This calls for a council and some thinking, John,” Stan said. “Come on below with me.”
He led the way down into the cabin while the Water Witch swung at her anchor, her sails flapping very softly in the night breeze. The little sloop had thick curtains, which he now drew over the cabin ports. Then he was heard to close the slide to the cabin entrance and come back down the steps. The sputter of a match in the darkness, and Stan was lighting one of the smaller cabin lights, which he set upon the cabin table upon which had been spread the chart of Porpoise Island and vicinity. There was a serious frown upon his features as the youthful skipper faced his chum across that table.
“Here’s the situation as I see it,” Stan said, speaking in a low voice. “This afternoon we saw a speedy motorboat of low, fast design, painted an inconspicuous gray and fitted with an almost silent exhaust, which disappeared round the snout of this island. Now we’ve come into Black Cove, a rarely visited spot, and find ourselves in the midst of symptoms of trouble—a fast, almost silent motorboat which comes in at night, blinking signals in answer to shore lights. Is this or is it not a dangerous spot? Are these innocent happenings, or should we get out of here and pronto?”
John considered the problem for a minute, for he knew Stan was in dead seriousness, and besides, he himself was creepy and scared.