Paying no heed to the occupants of the bully's boat, who, by reason of their daring, had been responsible for his accident that might have resulted seriously, Tom was soon at his dock. He had it conveniently arranged for hoisting craft out of the water to repair them, and in a few minutes the stern of the Arrow was elevated so that he could get at the rudder.

"Well, it's not as bad as I thought," he remarked when, with critical eye, he had noted the damage done. I can fix it in about an hour if Garret helps me."

Going up to the house to get some tools and to tell the engineer that he had returned, Tom looked out over the lake and saw Andy's boat moving slowly off.

"They've got her fixed up in some kind of shape," he murmured. "It's a shame for a chump like Andy to have a good boat like that. He'll spoil it in one season. He's getting altogether too reckless. First thing he knows, he and I will have a clash and I'll pay back some of the old scores."

Mr. Jackson was much surprised to see the young inventor home again so soon, as was also Mrs. Baggert. Tom explained what had happened, and he and the engineer went to work repairing the damage done by the Red Streak. As the owner of the Arrow had anticipated, the work did not take long, and, shortly before dinner time, the boat was ready to resume the interrupted trip to Sandport.

"Better stay and have lunch," urged Mrs. Baggert. "You can hardly get to the hotel by night, anyhow, and maybe it would be better not to start until to-morrow."

"No, I must get back to-night or dad would be worried," declared Tom. "I've been gone longer now than I calculated on. But I will have dinner here, and, if necessary, I can do the last half of the trip after dark. I know the way now and I have a compass and a good searchlight."

The Arrow was let down into the water again and tied outside the boathouse ready for a quick start. The dinner Mrs. Baggert provided was so good that Tom lingered over it longer than he meant to, and he asked for a second apple dumpling with hard sauce on. So it was with a very comfortable feeling indeed and with an almost forgiving spirit toward Andy Foger that our hero started down the path to the lake.

"Now for a quick run to Sandport," he said aloud. "I hope I shan't see any more of those men and that dad hasn't been bothered by them. His suspicions about the house weren't altogether unfounded, for I did see the tramp and some one else sneaking around, but I don't believe they'll come back now."

Tom swung around the path that led to the dock. As he came in sight of the water, he stared as if he could not believe what he saw, or, rather, what he did not see. For there was no craft tied to the string-piece, where he had fastened his motor-boat. He looked again, rubbed his eyes to make sure and then cried out:

"The Arrow is gone!"

There was no doubt of it. The craft was not at the dock. Breaking into a run, Tom hastened to the boathouse. The Arrow was not in there, and a look across the lake showed only a few rowboats in sight.

"That's mighty funny," mused the youth. "I wonder---"

He paused suddenly in his thoughts.

"Maybe Garret took it out to try and see that it worked all right," he said hopefully. "He knows how to run a boat. Maybe he wanted to see how the rudder behaved and is out in it now. He got through dinner before I did. But I should have thought he'd have said something to me if he was going out in it."

This was the one weak point in Tom's theory, and he felt it at once.

"I'll see if Garret is in his shop," he went on as he turned back toward the house.

The first person he met as he headed for the group of small structures where Mr. Swift's inventive work was carried on was Garret Jackson, the engineer.

"I---I thought you were out in my boat!" stammered Tom.

"Your boat! Why would I be out in your boat?" and Mr. Jackson removed his pipe from his mouth and stared at the young inventor.

"Because it's gone!"

"Gone!" repeated the engineer, and then Tom told him. The two hurried down to the dock, but the addition of another pair of eyes was of no assistance in locating the Arrow. The trim little motor craft was nowhere to be seen.

"I can't understand it," said Tom helplessly. "I wasn't gone more than an hour at dinner, and yet---"

"It doesn't take long to steal a motor-boat," commented the engineer.

"But I think I would have heard them start it," went on the lad. "Maybe it drifted off, though I'm sure I tied it securely."

"No, there's not much likelihood of that. There's no wind to-day and no currents in the lake. But it could easily have been towed off by some one in a rowboat and then you would not have heard the motor start."

"That's so," agreed the youth. "That's probably how they did it. They sneaked up here in a rowboat and towed the Arrow off. I'm sure of it."

"And I'll wager I know who did it," exclaimed Mr. Jackson energetically.

"Who?" demanded Tom quickly.

"Those men who were sneaking around---Happy Harry and his gang. They stole the boat once and they'd do it again. Those men took your boat, Tom."

The young inventor shook his head.

"No," he answered, "I don't believe they did."

"Why not?"

"Well, because they wouldn't dare come back here when they knew we're on the lookout for them. It would be too risky."

"Oh, those fellows don't care for risk," was the opinion of Mr. Jackson. "Take my word for it, they have your boat. They have been keeping watch, and as soon as they saw the dock unprotected they sneaked up and stole the Arrow."

"I don't think so," repeated Mr. Swift's son.

"Who do you think took it then?"

"Andy Foger!" was the quick response. "I believe he and his cronies did it to annoy me. They have been trying to get even with me-or at least Andy has---for outbidding him on this boat. He's tried several times, but he hasn't succeeded---until now. I'm sure Andy Foger has my boat," and Tom, with a grim tightening of his lips, swung around as though to start in instant pursuit.

"Where are you going?" asked Mr. Jackson.

"To find Andy and his cronies. When I locate them I'll make them tell me where my boat is."

"Hadn't you better send some word to your father? You can hardly get to Sandport now, and he'll be worried about you."

"That's so, I will. I'll telephone dad that the boat---no, I'll not do that either, for he'd only worry and maybe get sick. I'll just tell him I've had a little accident, that Andy ran into me and that I can't come back to the hotel for a day or two. Maybe I'll be lucky to find my boat in that time. But dad won't worry then, and, when I see him, I can explain. That's what I'll do," and Tom was soon talking to Mr. Swift by telephone.

The inventor was very sorry his son could not come back to rejoin him and Ned, but there was no help for it, and, with as cheerful voice as he could assume, the lad promised to start for Sandport at the earliest opportunity.

"Now to find Andy and my boat!" Tom exclaimed as he hung up the telephone receiver.