“He ought to make a darned good rural, if that’s so,” said the collector.  “But he is under arrest for smuggling.  He rode a horse across the line without declaring valuation.”

“Juan,” said the captain, “seize the horse of the Americano.”

“Juan,” echoed Waring softly, “I have heard that Pedro Salazar seized the horse of an Americano—­in Sonora.”

The rural stopped short and turned as though awaiting further instructions from his chief.  The collector of customs rose and sauntered to the doorway.  Leaning against the lintel, he lighted a cigar and smoked, gazing at Waring’s horse with an appreciative eye.  The captain of rurales, seated opposite Waring, rolled a cigarette carefully; too carefully, thought Waring, for a Mexican who had been daring enough to ride across the line with armed men.  Outside in the fading sunlight, the horses of the rurales stamped and fretted.  The cantina was strangely silent.  In the doorway stood the collector, smoking and toying with his watch-charm.

Presently the assistant collector appeared, glanced in, and grinned.  “The kid is asleep—­in the office,” he whispered to the collector.

Waring knew that the flicker of an eyelid, an intonation, a gesture, might precipitate trouble.  He also knew that diplomacy was out of the question.  He glanced round the room, pushed back his chair, and, rising, stepped to the bar.  With his back against it, he faced the captain.

“Miguel,” he said quietly, “you’re too far over the line.  Go home!”

The captain rose.  “Your Government shall hear of this!”

“Yes.  Wire ’em to-night.  And where do you get off?  You’ll get turned back to the ranks.”

“I?”

“Si, Senor Capitan, and because—­you didn’t get your man.”

The collector of customs stood with his cigar carefully poised in his left hand.  The assistant pushed back his hat and rumpled his black hair.

All official significance set aside, Waring and the captain of rurales faced each other with the blunt challenge between them:  “You didn’t get your man!”

The captain glanced at the two quiet figures in the doorway.  Beyond them were his own men, but between him and his command were two of the fastest guns in the Southwest.  He was on alien ground.  This gringo had insulted him.

Waring waited for the word that burned in the other’s eyes.

The collector of customs drew a big silver watch from his waistband.  “It’s about time—­to go feed the horses,” he said.

With the sound of his voice the tension relaxed.  Waring eyed the captain as though waiting for him to depart.  “You’ll find that horse in the corral—­back of the customs office,” he said.

The Mexican swung round and strode out, followed by his man.

The rurales mounted and rode down the street.  The three Americans followed a few paces behind.  Opposite the office, they paused.