“That’s very strange,” exclaimed the lad.  “There must be some mystery about my boat that I don’t understand.  But that will keep until I get the boat itself.  Good-by, Mr. Damon.  I must be off.”

“Where to?”

“Up the lake after those thieves.  I must lose no time,” and Tom started to go back to where he had left the red streak.

“Hold on!” cried Mr. Damon.  “I have something to propose, Tom.  Two heads are better than one, even if one doesn’t know how to adjust a nutmeg grate.  Suppose I come along with you?  I can point out the direction the men took, at any rate.”

“I’ll be very glad to have you,” answered the lad, who felt that he might need help if there were three of the thieves in his craft.  “But what will you do with your automobile?”

“I’ll just run it down the road a way to where a friend of mine has a stable.  I’ll leave it in there and join you.  Will you let me come?  Bless my eye glasses, but I’d like to help catch those scoundrels!”

“I’ll be very glad to have you.  Go ahead, put the auto in the barn and I’ll wait for you.”

“I have a better plan than that,” replied Mr. Damon.  “Run your boat down to that point,” and he indicated one about a mile up the lake.  “I’ll be there waiting for you, and we’ll lose no time.  I can cover the ground faster in my auto than you can in your boat.”

Tom saw the advantage of this and was soon under way, while he heard on shore the puffing of his friend’s car.  On the trip to the point Tom puzzled over the strange actions of the man in taking one of the braces from under the gasoline tank.

“I’ll wager he did it before,” thought the lad.  “It must be the same person who was tampering with the lock of the forward compartment the day I bought the boat.  But why—­that’s the question—­why?”

He could find no answer to this, puzzle over it as he did, and he gave it up.  His whole desire now was to get on the trail of the thieves, and he had strong hopes, after the clew Mr. Damon had given him.  The latter was waiting for him on the point, and so nimble was the owner of the auto, in spite of his size, that Tom was not delayed more than the fraction of a minute ere he was under way again, speeding up the lake.

“Now keep well in toward shore,” advised Mr. Damon.  “Those fellows don’t want to be observed any more than they can help, and they’ll sneak along the bank, They were headed in that direction,” and he pointed it out.  “Now I hope you won’t think I’m in the way.  Besides, you know, if you get your boat back, you’ll want some one to help steer it, while you run this one.  I can do that, at all events, bless my very existence!”

“I am very glad of your help,” replied the lad, but he did not take his eyes from the water before him, and he was looking for a sight of his boat with the men in it.

For three hours or more Tom and Mr. Damon cruised in and out along the shore of the lake, going farther and farther up the body of water.  Tom was beginning to think that he would reach Sandport without catching sight of the thieves, and he was wondering if, after all, he might not better stop off and see his father when, above the puffing of the motor in the red streak, he heard the put-put of another boat.