Somehow he did not find himself taking any great amount of stock in this theory. Why, had it been easy-going Bumpus now, or even rather careless Step-hen, Thad fancied that there might have been more or less truth back of the suspicion; but unless his study of the tenderfoot had been wrong, Smithy would not be guilty of disobedience.
"Well, what am I thinking about?" was the way Thad took himself to task presently; "trying to find the answer to a riddle by bothering my brains, when it ought to be written here on the sand as plain as print."
Immediately he commenced to move about, looking for signs. Of course there must be all manner of footprints there, some recent, and others made on the occasion of the preceding visit of the scouts. But Thad had studied trail finding more or less under the watchful eye of the Maine boy, who knew considerable about it; and hence he was able to decide what were new, and what old footprints.
And he had not been at this task more than half a minute when he received considerable of a shock.
"Why, here's that footprint with the marked sole!" he whispered, a new thrill in the region of his heart.
He could guess what that meant, for it was very fresh and new. The man whom he now believed to be some sort of criminal, had been right there on the beach since he, Thad, had quitted the spot to climb the tree selected for his signaling operations!
And since Smithy was supposed to be waiting there, only one inference could be drawn—the tenderfoot scout had fallen into the enemy's hands!
Evidently matters were approaching a crisis now. The two men who hid on this island as though they feared their fellows to see them, were beginning to grow bolder. At first they had only felt annoyed by the coming of the scouts, and the making of the camp opposite their secret retreat. Then, by degrees, as the boys began to infringe on their territory, they had commenced to strike back; first by causing the boat to disappear; and now by capturing poor Smithy, who must be nearly dead with fright because of his peril.
Thad suspected the men may have begun to fear that their hiding-place was known, and that the boys would be trying to either effect their capture, or communicate their discovery to the authorities in some neighboring town.
Perhaps they hoped to keep matters boiling at fever heat until night fell, when they could make use of the recovered boat to slip away; or else swim from the island retreat.