Of course, it wasn't a wagon. Nor was it a huge box. Neither wagon nor box could have got out here, fifteen or twenty rods off Gannet Island. Wyn glanced over toward the island and saw that she could look right into the cove where John Jarley had met with his accident. According to the boatman's story, as he went overboard from the motor boat he gave the wheel a twist that should have shot her directly out of the cove toward the middle of the lake. "But suppose the boat didn't respond, after all, to the twist of the wheel?" Wyn was thinking. "Or, suppose the slant of the rudder was not as great as he supposed?" She fixed in her mind about the spot where the thing lay she had hit, and then glanced back to the tree on the bank of the cove, that showed the long scar where the branch was torn off. The line between the two was clear. The motor boat might have run out exactly on that course and missed the wooded point which guarded the entrance to the cove. Suppose the thing she had hit when she dived was the _Bright Eyes_, Dr. Shelton's lost motor boat? Wyn was about to shout to the other girls--to call them around her to divulge the idea that had come into her mind--when a hail from the water announced the return of the Busters. She remembered Mr. Lavine's promise. The two clubs were rivals in this matter. Wouldn't it be a fine thing for the Go-Aheads to own a motor boat all by themselves! Wyn got up and dived again. But she did not dive toward the mysterious something that she had previously found. She swam stoutly instead to meet the coming Busters. CHAPTER XXIV THE NIGHT ALARM Wyn Mallory had "another mind," as the saying is, before the Go-Aheads left the island and paddled swiftly for their own camp. She determined not to say anything to her girl friends of the club about the sunken object she had hit under the water. Perhaps it was nothing of any consequence; then they would laugh at her. If it _was_ the lost motor boat, to tell the girls might spread the story farther than it ought to be spread at once. The Go-Aheads and the Busters were rivals. Mr. Lavine had promised the prize to whichever club found the sunken boat and the box of silver images that Dr. Shelton had accused John Jarley of stealing. "And it may not be anything, after all," thought Wyn. "It may be a false alarm. Then the _boys_ would have the laugh on us." To make sure of what she had hit when she dived seemed to Wyn to be the principal thing. And how could she make sure of this without going down specially to examine the mystery? "How under the sun am I going to do that without the boys seeing me?" she mused. "And if I take the girls into my confidence they will all want to be there, too--and then sure enough the Busters will catch us at it. Dear me! I don't know what to do--really."