"And suppose we do?" asked Bart.
"Well, we'll know where it is," Ned went on. "That's something. We may not see Frank, but perhaps we can find out if he is there. It's worth trying. I can't sit still and do nothing."
They started to follow the telephone line the next day. They found it did lead to the sanitarium but not wishing to show themselves near the building, they did not approach closely. They remained hiding in the woods, hoping they might catch a glimpse of their chum, but he did not show himself.
"I guess the only thing for us to do is to return to camp," suggested Bart. "We'll have to wait until Frank comes away and tells us what he has been doing."
Rather sorrowfully, they went back to camp. The two days that followed were lonesome ones. None of the three felt like doing anything. They did not fish, and even the canoe had lost its charm. They sat around under the trees, and, for the twentieth time, talked over the situation in regard to their missing comrade.
"It looks as if the Darewell Chums would number three instead of four, after this," said Fenn rather mournfully, on the morning of the third day of Frank's absence.
"Don't be a calamity howler!" exclaimed Ned. "Frank will come back to us. The chums can't be separated."
"I hope that's true," put in Bart, from where he was sitting under a tree, smoothing one of the canoe paddles. "All our fun will be spoiled if we have to break up the quartette.
"Hark! What's that?" asked Fenn, sitting up suddenly.
They all listened. There was the sound of someone approaching through the bushes.