CHAPTER XXI.

OFF ON A SEA TRAIL.

As minutes and then hours elapsed and Rob did not return, Merritt became first anxious, and then seriously alarmed. He knew Rob's daring nature, and had a keen fear that it might have led him into doing something reckless.

It was almost dawn when he at length determined to return to the encampment and seek out Ensign Hargreaves. By the time he had tramped back over the sandy dunes day was breaking, and in the camp of the Boy Scouts the notes of the morning bugle were ringing out cheerily. The first of the Scouts to note Merritt's return was Donald Grant.

He came running toward him, and then stopped short as he noted the other's drawn, tired face.

"Why, what in the world's the matter with you, Merry?" he gasped out.

"You look as if you'd been drawn through a knothole. Where's Rob? Where have you been all night?"

"I'll explain that later," said Merritt wearily; "just now I've got to find Ensign Hargreaves. Rob's either been kidnapped or lost."

He hastened on, leaving the other lad rooted to the spot with amazement and alarm. He knew Merritt well enough already to realize that the other was not the sort of lad to overrate a situation. If Merritt was as scared and weary as he looked, something serious indeed must have taken place.

In the meantime Merritt hastened to Ensign Hargreaves' tent. Hastily arousing him, he hurriedly explained the whole matter. The officer was out of his cot in an instant.

"You had no business to go off alone like that without notifying me,"

he exclaimed rather sharply. "Don't you know that the first duty of a soldier, a sailor or a scout is to obey orders?"

Merritt crimsoned and hung his head. He knew that the officer was right.

"We thought we were doing a good thing," he said, "but I know now that we did wrong in not notifying you."

The ensign's hand fell on the lad's shoulder. Then kindly enough he said:

"Well, acknowledging that you did wrong is a manly thing, my boy, and we'll say no more about the matter. But about Rob, something must be done right away. Arouse Mr. Barr while I am dressing and we'll set about searching for him at once. There's little doubt in my mind but that he is on that island where you saw the signals flying."

"But how could he get there unless he had an airship?" inquired Merritt.

"Hasn't it occurred to you that he might have hidden in the boat while the men were out of it?"

"Gracious! In that case he may be their prisoner by this time!"

"I am afraid that there is little doubt of that. We must get after the rascals at once."

By the time the ensign was dressed, Mr. Barr was also attired, and the two immediately began a discussion of plans for the rescue of Rob. But first the ensign wanted to know about Barton.

It was hard for Mr. Barr to believe that the man whom he trusted implicitly could have proved traitor to him.

"The best way to find that out is to look at your papers and models and see if anything is missing," was the response.

"I'll do so; but I'm sure the boys must be mistaken in Barton. He has worked for me for many years."

"Possibly the large price he was offered to turn over the plans of the _Peacemaker_ had something to do with it," suggested Merritt.

"Perhaps; but I'll not say anything till I find out definitely that something is missing."

Mr. Barr hastened off toward the shed, but returned before long with a countenance filled with apprehension.

"My most important blue prints and models are missing!" he exclaimed.

The ensign made a dry grimace.

"Our young friends were right," he said. "In detecting the rascal they have done an excellent piece of scouting work. But now let us hurry off in search of Rob at once."

"How will you reach that other island?" asked Merritt.

"We will go in the motor boat. She is fast and does not draw much water."

"Can we all go along?"

"No, we'll take one of my sailors, your chum Donald, Tubby Hopkins, you and myself. We haven't settled accounts with Barton yet, and I don't want him left practically alone on the island."

"Do you think he would try to harm the submarine?"

"I think it likely. He has probably been paid to injure it so that the rival power that is working against us can construct its submarines first."

"But you are going to make him confess?"

"If he will, yes. If not, he faces a long prison term, although it will be hard to prove that he actually stole the papers and models."

"But we saw him answering those signals, and then again, last night we saw him meet the men."

"I'm afraid that wouldn't make very good evidence in a court of law,"

was the rejoinder. "But enough of this now. Tell Hawkins (one of the sailors) to get the boat ready, and hurry through your breakfast We'll start right afterward."

"We can't start too quick for me," was the brisk reply. "Poor old Rob, I wonder what has happened to him."

While he ate a hasty meal Merritt outlined to the other Scouts what had happened. Following this, Ensign Hargreaves announced a change of his plans. He had decided, he said, to take Barton along, not caring to leave the man on the island.

"He is clever and dangerous," he said, "and I want him under my eye till I have decided how to dispose of his case."

"You are not going to let him know you suspect him?" asked Merritt.

"For the present, no. As to what I shall do in the future, I have not yet made up my mind."

Ten minutes later a black motor boat shot out of the little inlet in which she had been moored. As she sped seaward, making for the other island, those left behind set up the cry of the Eagle and Wolf patrols.

Barton, looking sullen and suspicious, was at the engines. He knew the object of the trip, but, of course, had no knowledge that his part in it was suspected. Nor did any of the party show him by looks or words that so much as a breath of suspicion attached to him. This was by the orders of Ensign Hargreaves, who had determined to give the fellow plenty of rope.

As the _Viper_, as the black motor boat was called, raced over the water, Merritt found himself gloomily contemplating the future. If anything serious had happened to Rob, he felt that he would be in a measure responsible for allowing the young leader of the Eagles to go off alone.

CHAPTER XXII.