"We're attacked!" came a voice.
At the same instant the sound of a distant volley resounded.
"Hooray! Nat made good!" yelled Cal, leaping about and cracking his fingers.
The next instant a rapid thunder of hoofs, as the outlaws wheeled and made off, was heard. As their dark forms raced by, the posse headed by Sheriff Tebbetts and Nat, fired volley after volley at them, but only two fell, slightly wounded. The rest got clear away. A subsequent visit to their fortress showed that on escaping from the posse they had revisited it and cleaned all the loot out of it that they could. The express box stolen from Cal's stage was, however, recovered.
As the posse galloped up, cheering till the distant canyons echoed and re-echoed, the besieged party rushed out. They made for Nat and pulled him from his horse. Then, with the young Motor Ranger on their shoulders, they paraded around the hut with him, yelling like maniacs, "'For he's a jolly good fellow'!"
"And that don't begin to express it," said the sheriff to himself.
"He's the grit kid," put in one of the hastily-gathered posse admiringly.
And the "Grit Kid" Nat was to them henceforth.
The remainder of the night was spent in the hut, Nat telling and retelling his wild experience in the flume. The next morning the posse set out at once at top speed for the fortress of Morello, the sapphire chest being carried in the auto which accompanied the authorities. Of course they found no trace of the outlaws; but the place was destroyed and can never again be used by any nefarious band.
Nat and his friends were anxious for the sheriff to take charge of the sapphire find, but this he refused to do. It remained, therefore, for the Motor Rangers themselves to unravel the mystery surrounding it.