to be sure no one was listening.

“It is like this,” he continued. “President Madero has discovered that there is a real plot on foot to start another revolution and overthrow his government. Arms for the revolutionists would have to come from this side of the river. As a revolution is unlawful, carrying arms across the Rio Grande to help a revolution is unlawful, and he has asked Uncle Sam and the State of Texas to prevent any guns or ammunition from going into Mexico which do not go through the Mexican custom house.”

“It looks to me,” broke in Billie, “as though that was the business of the Mexican government.”

“So it is,” replied Captain Peak, “but as long as Mexico is a friendly nation it is also our business to prevent filibustering—and that is what gun running amounts to.

“There is also another reason for helping to prevent this sort of smuggling. We frequently have to ask the Mexican government to aid us in running down outlaws who escape into that country. If we don’t help them, they won’t help us. So you can see, if we can learn anything about this revolutionary movement, it will be a good thing. You boys,

because you are strangers and travelers, are just the ones to help. What do you say?”

For several moments the boys said nothing, but finally Donald replied that if the captain would give them a few minutes to talk the matter over between themselves, they would be able to let him know.

“All right,” was the reply, “I’ve an appointment with the mayor, which will give you all the time you need,” and he left the hotel to keep his appointment.

“Well,” remarked Billie, as the captain disappeared around the corner, “what do you think of that?”

“I don’t think anything of it,” replied Donald. “I’ve no liking for that kind of work.”

“Why not?” queried Adrian.

“I don’t know. I just haven’t, that’s all.”

“You’d like to prevent war, wouldn’t you?”

“Sure,” was Donald’s emphatic rejoinder; “but I can’t see how this trip can prevent war.”

“I don’t know as it would,” said Adrian, “but, if we could do anything which would keep a lot of dissatisfied peons from getting guns and going out and killing people, it seems to me we would be doing a good deed.”

“That’s just the way it seems to me,” declared Billie. “The average Mexican who wants to start a revolution looks to me a good deal like the fellows who stole our mule.”

“Not necessarily,” replied Adrian. “Sometimes revolutions are started by men to overthrow a bad government. But my mother has always taught me there was a better way to right a wrong than to go to war over it. That’s why I am in favor of doing all we can to help those who want to prevent trouble.”

“Of course if you put it that way,” said Donald, “I’ve no objection to the excursion, as the captain calls it.”

When Captain Peak returned, they unanimously announced their readiness for the trip, and, half an hour later, fully instructed as to what was expected of them, they were across the Rio Grande, engaged upon what proved to be the most important adventure of their career.

CHAPTER IV.—A FRIEND IN NEED.

“This is certainly a funny excursion,” laughed Billie, after the boys had ridden along in silence for some minutes. “It’s like looking for a needle in a haystack.”

“How so?” queried Donald.

“Well, isn’t it? This big country is the haystack, and the bunch of gun runners is the needle. I see mighty little chance of finding them.”

“Oh, I don’t know,” replied Donald. “We never started out to find anything yet that we didn’t locate it—even old Bray,” he added as an afterthought.

“That’s right,” chimed in Adrian. “There is nothing like having your luck with you.”

“Huh,” grunted Billie, “I’m not sure but the greatest luck we could have would be not to find anything.”

Adrian looked at the speaker in surprise.

“It’s the first time I ever knew you to show the white feather,” he said.

“Who’s showing the white feather?” demanded Billie, with much spirit. “I’m just as anxious as

anyone to put a stop to lawlessness; but you wouldn’t call any man a coward, would you, because he wouldn’t deliberately stick his head in a hornet’s nest?” And he gave his horse a vicious dig with his spurs.

“Oh, don’t get mad about it,” said Adrian. “I didn’t mean to hurt your feelings.”

“Well, then, don’t be accusing me of showing the white feather. There’s a whole lot of difference, in my mind, between being a coward and using a little common sense.”

“He has the best of you there, Ad.,” remarked Donald; “when it comes to doing things, Billie will be on the job.”

Donald’s words were like oil on the troubled waters, and after a few minutes Billie continued in a voice entirely free from any irritation:

“The thing I can’t understand is this: If somebody has so much information as to what is to be done, why don’t they have some little knowledge of those who propose to do it? The whole thing looks fishy to me.”

“I believe you’re right,” assented Adrian, after turning the matter over in his mind for several minutes. “There is something kind of mysterious about it.”

“I don’t see it,” declared Donald, “but, even if there is, all we have to do is to keep our eyes and ears open. We have the law on our side.”

“Looks like mighty little law to me,” replied Billie, who, for some reason or other insisted upon looking on the dark side. “But, to change the subject, what do you call that?” and he pointed away to the south, where a cloud of dust was to be seen.

“Looks as though it might be a herd of cattle.” said Donald, after a moment’s inspection. “Although,” he added, after further observation, “it would be a mighty small one.”

“They certainly make a lot of dust,” was Adrian’s comment, followed in a moment with: “Look! Look! It’s a race! It’s a race!”

A race it certainly was, in which something less than half a dozen horsemen were engaged, and the boys drew rein to watch it.

At the first glance it did not appear to be very exciting, as one of the riders was so far in advance that there seemed very little chance for any of the others. But, as the boys watched the flying horsemen, it slowly dawned upon Donald that there was something wrong.

“By George!” he suddenly exclaimed, “I don’t believe it’s a race at all. It looks to me as though there were three trying to catch one, and I don’t think it’s for any good purpose.”

“I believe you’re right, Don; and, look,” exclaimed Adrian, “they’re headed this way!”

That the boys were right was fully evidenced as the flying horsemen approached. The pursuers

seemed to be men, while the fugitive was a lad of about the same age as our travelers.

All at once the boy espied the Broncho Rider Boys, and, digging his spurs into his horse, turned abruptly and rode directly toward them.

“Socorre mi! Socorre mi!” he called, as he came within hailing distance.

“What does he say?” asked Billie.

“He’s crying for help,” replied Donald. “What had we better do?”

“Help him, of course,” replied Billie.

“And get ourselves into a lot of trouble for our pains,” declared Donald.

“Who cares! Three to one is more than I can stand,” and Billie yanked his Marlin from its sheath at his saddle girth.

Seeing that Billie intended to interfere, even if he had to go it alone, Don and Adrian