r a thought of the grotesque mistake, both youths had boarded
the launch believing it to be the _Deerfoot_; they had pursued the
imaginary fugitive only to awaken to the fact that she was not a
fugitive, and that they had unconsciously stolen the property of the
burglars, which must have been lying so near their own craft that the
slight difference of location was not noticed.

Chester stepped down and seated himself at the elbow of his chum.

"Here are only four seats instead of six. Why didn't we notice it
before?"

"Because we were too much occupied with other things, or rather were both
struck with blindness just then. As Mike would say, I'm completely
flabbergasted."

"And I'm with you. What's to be done now?"

"Tell me where the _Deerfoot_ is."

"Ask me something easier. She may be lying where we left her, or twenty
miles away."

"We should have heard her if she came down stream."

"She may have gone up the river and around into the Sheepscot."

"And back to the former hiding place of this boat or to a different
one--the 'Beautiful Isle of Somewhere,'" said Alvin grimly.

"One place will serve as well as another. I wonder whether there was ever
so wonderful a mix-up of launches since such craft were known."

Alvin shut off power and the two listened. From some point miles away
came the hoarse growl of a steam whistle, but all else was still. He had
hoped that they would hear the _Deerfoot's_ exhaust, but nothing of the
kind came to their ears. He flirted the switch around and resumed the
speed which was not above half a dozen miles an hour.

One of the plagues of the Maine coast is the dense fogs which sometimes
creep far up the rivers. Such an obscurity now began settling over
Montsweag Bay and Back River, shutting out the moonlight as well as the
rays of the rising sun. Before Alvin was aware, he could not see either
shore until he had run far over to the right and caught a shadowy sight
of the pines, spruce and firs which lined the bank. The air dripped
moisture and, though it was summer, it grew chilly.

While gliding slowly forward they heard a steamer's bell, accompanied by
occasional blasts from her whistle. She was feeling her way down stream
and sounding warnings to other craft. By and by the beat of her screw and
the ripple of the water from her bow sounded so near that Alvin edged
closer to land. In the heavy mist loomed a minute later a bulky steamer,
surging southward at sluggish speed,