"I'd like to know more about them. There was something funny about the way they chased us in the boat. And don't you remember how closely they looked at Chet and Biff? It seems funny to see them hanging around the farm."
"Well, they haven't done us any harm. I suppose it's none of our business—but I'd sure like to know what their game is. Let's find Chet and tell him."
They increased their speed and before long overtook Chet Morton on the shore road. But Chet laughed at their fears.
"You're too suspicious," he said. "They had probably just stopped to fix a tire when you came along. However, we'll go back to the farm and see if they're still on hand."
But when the boys drove back to the Morton farm they found that the mysterious trio in the automobile were no longer in sight.
CHAPTER IV
The Send-Off
On Monday, Chet Morton and Biff Hooper set out on their motorboat trip up the coast. They were well equipped with provisions and supplies and had been up since six o'clock that morning getting the boat in readiness.
The Hardy boys went down to the dock to bid them good-bye, and although they chaffed the adventurers and laughed with them, neither Frank nor Joe could repress the disappointment they naturally felt at being unable to go with their chums.