“I haven’t seen any further flashes, Jack. Have you?”

“No, Frank. Bob, what do you make of it?”

“Well, you know more about radio than we. As far as I know, that light wasn’t any indication that the radio was in use, because there is no such indication possible.”

“You’re right, of course, Bob. That light was a signal to somebody somewhere. I wonder——”

“What?” asked Frank.

“Whether it was a signal to some ship off shore?”

“Or to the smugglers who are inland,” suggested Frank.

“It might have been the latter,” said Jack. “I hadn’t thought of that. Let’s see whether this hilltop commands a view up the canyon.”

They had paused beside a clump of rocks some thirty feet from the nearest corner of the radio station, after toiling up the steep slope. They spoke in whispers. Not a sign of life was apparent about the station, yet they could not have been deceived regarding the appearance of the lights, ere starting to climb upward. What did it mean? It was this they had been discussing, and now, at Jack’s suggestion, they faced about. A smothered exclamation broke from Jack’s lips:

“Why, this hilltop must be in sight for miles.”

Even in the moonless darkness, it was apparent that such was, indeed, the case. The winding canyon, up which had disappeared Ensign Warwick and his relief party going to the aid of Inspector Burton in his fight with the smugglers, was commanded for a long distance by this outjutting hill on which the radio station had been erected. Two rows of hills, shadowy, bulking in the darkness, stretched ahead on either side and the canyon lay between.

“Fellows, our arrival and landing was watched,” whispered Frank, with conviction. “Then when Ensign Warwick set out with his men, the spy signaled from here by means of a light. And so the smugglers were informed and forewarned.”

“Yes,” said Bob suddenly, “and say——”

The big fellow did not often speak, but when he did it was usually to the point. Bob and Jack looked at him.

“Say what?” asked Jack.

“Why, that Chinaman Charley Lung. I’ll bet he’s in on it. He’s leading our men into a trap.”

“I believe you’ve guessed it, Bob,” said Frank, his low voice taking on increased excitement. “Remember how he looked?”

“Looked like a heathen idol to me,” grunted Bob. “What do you mean?”

“Oh, a kind of sly look in his eye, and something sly in his voice, too. ‘All light,’ he said. ‘Come ’long.’ I tell you, now that Bob has suggested it, I believe that Chinaman was planning to play the traitor, and lead Ensign Warwick into an ambush.”

For several seconds all three crouched there beside the rocks, thinking. And their thoughts were not of the pleasantest. Their party was split. Inspector Burton with one force was somewhere inland engaged with the smugglers. Perhaps he had encountered a large force, and was hard pressed. Certainly, the sound of firing had grown more and more distant until it could no longer be heard, and that seemed to indicate he was being beaten back.

Then there was Ensign Warwick with the second force. And, if their surmise was correct, the smugglers had been informed by signal from the radio plant that he was coming, and Charley Lung, moreover, was leading the naval force into a trap.

“What could they do? What could they do?”

That was the question in each mind. Instinctively, as always in a crisis, the others turned to Jack.

“First of all,” said Jack, “we have got to find who is in the radio station, and capture him. It won’t do to leave an enemy in our rear.”

“What if there is more than one,” objected Frank.

“Not likely,” said Jack. “One man to spy and give the signal would be sufficient. More would be a waste of men.”

“All right. Let’s go,” said Bob. When action was suggested, he always was ready for it.

Jack considered.

“Listen. We want to be careful, and not run unnecessary risks. It’s just a little box of a station with a window in this end nearest us, a door there in front, and probably a window on the other end. I think that window is too small for a man to escape through, don’t you?”

The boys agreed.

“Big enough for pigeons,” commented Bob. “That’s about all.”

“Well, see what you think of my plan. We’ll creep up to the door, and crouch to each side of it, then knock and call on whoever is within to come out and surrender.”

Bob and Frank considered.

“Sounds all right to me,” said Frank.

“Why not break right in?” grumbled Bob.

Jack shook his head.

“Best to be cautious,” he said. “Let’s go.”

Slowly and with infinite care so as not to dislodge loose stones and set them rolling down the hillside or to make any betraying sound, the boys crept to their chosen positions, Bob and Frank on one side of the door, Jack on the other. The revolvers served out to them by Ensign Warwick were held ready. Not a sound from within. Was their presence known or suspected?

Jack leaned forward and thumped on the door with the butt of his weapon.

“Come out,” he called in a clear, firm voice, “in the name of the United States Navy I call on you to surrender. Your light was seen from the warship, and the station is surrounded.”

A moment’s silence followed. The hearts of the boys beat so strongly it seemed to them the very sound must be heard in that tense stillness. Then the boards of the floor creaked under a light tread, and the door was slowly pulled inward.

“Don’t shoot,” said a voice. “I surrender.”

A slender form appeared in the doorway, hands upraised. Jack shot the rays of his flashlight upward. A Chinese youth in American clothes appeared. He was spectacled.

“Are you alone?” demanded Jack.

“Yes, sir.”

“Armed?”

“Yes, sir.”

“Advance and be searched.”

The youth stepped across the low sill of the station, hands still upraised. Jack motioned to Frank to search him, and the latter ran his hands over the other’s form, abstracting a revolver and a long knife.

“That all?”

“Yes, sir.”

Bob spun the young Chinaman around, pulled out his belt and tied his hands together with it.

“Keep an eye on him,” said Jack. “I’m going to have a look at the station.”

First casting the rays of his flashlight over the interior and verifying the Chinaman’s statement that he was alone, Jack went inside. Presently Bob and Frank heard him exclaim, and then he appeared in the doorway lugging a heavy square wooden box.

“Look what I found,” he cried delightedly. “A portable radio outfit for field work. This is the very latest equipment. I’ve examined it hastily, and it seems to have everything—antennae coiled up and ready for stringing, some jointed steel poles to attach it to the box and powerful storage batteries.”

“What’ll we do with it?” asked Bob.

“I don’t know yet, but I have a hunch it will come in handy. Well, now I guess we better go down to the boat and tell this man Robbins what we have discovered and what we suspect. Then we can talk to our prisoner, too.”

The latter’s face was impassive. In appearance and judging by the choice of words he had employed, he was an educated youth. Perhaps something could be gotten out of him by questioning. It was worth trying.

“All right,” said Bob. “Frank, you watch our prisoner and I’ll lend Jack a hand with this radio outfit.”