"It is of no use, Senor," he said to Frank, who had jumped from the running board and stood beside him. "She is finish. The spark plug, she is on the—what you call it?—the bum." And with an air of finality, he closed the cover. At the same moment he turned to peer anxiously down the road ahead, whence came now on the still twilight the thudding hoofbeats of a galloping horse, rapidly growing louder.

His mechanical instincts awake, however, Frank paid no attention to the approaching horseman. He had again lifted the cover, as Remedios turned away, and, lighted match in one hand, was twisting at a spark plug with the other.

"Shucks," he cried, withdrawing his head, "that Number One plug wasn't screwed in tightly enough, that's all. I'll bet she'll go now, just the way I tightened her by hand. And if I only had a pair of pliers——"

At that moment, the galloping horseman dashed up alongside, pulling his horse back on his haunches. It was Gabby Pete, his hat gone, his face red with excitement. Far over he leaned to call to the astonished occupants of the car.

"Bandits," he cried hoarsely. "Greasers. Comin' in an auto. I come back to warn you." And facing about he pointed to where a cloud of dust behind him on the desert road indicated a rapidly oncoming car.

"Grab that crank," cried Frank to Remedios, and he sprang for the driving wheel. "I'll make this old bus go."

"Not so fast, Senor," said Remedios suavely, and seizing Frank's arm he whirled the young fellow about.

Frank looked into the muzzle of a revolver which Remedios held leveled at him.

CHAPTER X

A BRUSH WITH THE ENEMY