with a puzzled frown

  They carried the limp body within the shack and laid it tenderly on the couch. There was still life, and they worked with prayers on their lips. . . .   From outside broke two sharp whistles. Mahon, with a puzzled frown, looked from the front door. An awkward little broncho was trotting past the corner of the house toward the stable.   Williams came to him. "I'm afraid it's no use, sir," he whispered. "Nothing could stand up under that."   Mahon appealed to his wife. "Help us, Helen, it's got past us."   The sudden thunder of hoofs along the river side of the shack drew the two Policemen to the door. Three horses, the broncho in the lead, were climbing the grade. The broncho started out on the trestle, head bent, measuring each step, moving from sleeper to sleeper. And at its heels, obedient as sheep, were Torrance's two horses.   Six hundred yards of open trestle before the fill-in at the other side! Mahon held his breath. . . .   "Mother o' Mike!" The horses had trotted out to safety, and Murphy was capering gleefully about.   Mahon rushed to the corner of the shack and looked about. The Indian was nowhere in sight.   Helen, with wet cheeks, was bathing the white face of the contractor. Tressa, searching Helen's eyes for hope, saw it vanish in those tears. With a crooning cry she sank beside the couch and lifted her father's head in her arms.