"Are you going to send these cases ash.o.r.e, sir?"

"Not until daylight. We must not forget that there may be another expedition attempted at some other point. Mr. Overton, I begin to think that this may be the point chosen for the shipment of arms enough for fitting out a whole rebel army in Mexico. I think I will go back to camp, now, and question Guarez. I may find him in a mood to talk."

"And my orders, sir?"

"Make this boat your headquarters. Do not leave here until I return, Mr.

Overton."

"Very good, sir."

"It was a pretty slick way that you caught us," began the mate, lounging near Hal as he stood on deck.

"Then you admit that this boat was engaged in an attempt at smuggling arms over the border?" demanded the young lieutenant, wheeling quickly.

"What's the use of denying it," questioned the mate, "with such cargo as we have?"

"Very little use indeed," Hal rejoined. "How much were you to get as your share of the night's work?"

"Oho! I didn't say that I had even a suspicion of what the game was,"

retorted the mate coolly. "I could only suspect, at best. You can't trap me into saying anything that would send me along to share Captain Boggs's fate."

"You're smooth enough," nodded Lieutenant Overton, "but don't try to play any further tricks."

"With United States troops aboard? What do you take me for?" grumbled the mate.

Hal didn't feel much inclined to talk with the fellow, so he stepped forward, leaving the mate by himself.

Half an hour pa.s.sed. Truth to tell, the young Army officer felt the monotony of his present position, confined to the boat and the pier.

Pa.s.sing the sentry at the gang-plank, who stood at present arms in salute, Hal Overton walked forward to the outer end of the pier. He had stood there some ten minutes, when, two or three miles up the river, he thought he saw a brief flash.

"That might have come from a search-light, swiftly operated," thought Lieutenant Hal, with a start. After a moment's reflection, he hurried on board the boat.

"Mate," he directed, "shove off and steam out just past the end of the pier."

"Why----" began the mate wonderingly.

"Obey the order, sir!"

As the boat moved slowly into open water Hal, standing by the search-light, gave another order:

"Switch on this light, mate."

"But your captain said----"

"Switch on the light, man! Be quick about it!"

As the light gleamed out Lieutenant Hal turned its broad flare up the river. Just on the edge of the beam he picked up a motor boat of considerable size. The other craft was some three miles up the river, headed due south across to the Mexican border.

In the instant that the man in charge of the motor boat discovered the search-light, he crowded on more speed.

"My plain orders are to remain here," quivered Lieutenant Hal to himself. "If I obey, even during a five minutes' delay, that craft will outfoot us to Mexico, and a cargo of arms will be on the other sh.o.r.e.

There's no time to communicate with Captain Foster. What on earth shall I do--disobey and face the chance of trial for disobedience of orders?"

CHAPTER XVI

AFTER SWIFT GAME

It was a ticklish position, and one that called for quick decision.

If Lieutenant Overton ordered the tug back to the pier and remained where he was, he would be but obeying explicit orders. No blame could afterward attach to him, no matter how many boats got across.

At the same time the young Army officer knew that he was stationed here for the express purpose of preventing any arms being smuggled over to Mexico.

"Even though I capture a boat with ten thousand stands of arms aboard,"

flashed swiftly through the Army boy's mind, "Captain Foster can still say that I disobeyed orders. Yet if I obey orders there's no telling what mischief may be done."

"Yet it seems to me that, when I am set to watch a violation of the national law, my first duty is to try to catch any one who attempts to violate the law," quivered the lieutenant.

Suddenly Hal turned to the mate.

"Go ahead, man--full speed! Catch that boat yonder!"

No reply did the mate make, but he rang one bell for half-speed ahead.

This he presently followed with the signal for full speed. The tug's propeller churned the water astern. For a craft of this kind the tug was now moving fast. Hal steadily held the ray of the search-light on the stranger.

"Can't you hump a little more speed out of this tub?" the young officer demanded.

"I can't signal for any more," replied the mate, his hands on the spokes of the wheel. "Why don't you ask the engineer?"

Young Overton quickly summoned a soldier and sent him to the engineer with a message calling for more speed. After another minute the increase in speed was easily discernible.

"But that boat's getting away from us," cried Lieutenant Overton, with irritation in his voice.

"Of course she is," spoke the mate gruffly. "I could have told you that she'd show us a clean pair of heels."

"What craft is she?"

"I don't know," the mate replied.

"Then how do you know she can beat us?"

"By her build. She's a costly gasoline boat, and such craft usually have high-power engines in 'em."

Hal sent another message to the engineer, who, however, sent back word that he was doing the best he could until draft made the fires under the boiler hotter.