A moment there was silence—­a silence of even the breath in Philip’s body, the beating of his heart.  His arms loosened a little.  He drew himself up rigid, and the girl lifted her head a trifle, so that their eyes met squarely, and a world of question and understanding passed between them in an instant.  As swift as morning glow a flush mounted into Isobel’s face, then ebbed as swiftly, and Philip cried:  “You were hurt—­hurt back there in the wreck.  But you’re safe now.  The train was wrecked by outlaws.  We came out after them, and I—­I found you—­back there on the prairie.  You’re safe now.”

His arms tightened about her again.

“You’re all right now,” he repeated gently.  He was not conscious of the sobbing break in his voice, or of the great, throbbing love that it breathed to her.  He tried to speak calmly.  “There’s nothing wrong—­nothing.  The heat made you sick.  But you’re all right now—­”

From beyond the hill there came a sound that made him break off with a sudden, quick breath.  It was the sharp, stinging report of Billinger’s carbine!  Once, twice, three times—­and then there followed more distant shots!

“He’s come up with them!” he cried.  The fury of fight, of desire for vengeance, blazed anew in his face.  There was pain in the grip of his arm about the girl.

“Do you feel strong—­strong enough to ride fast?” he asked.  “There’s only one man with me, and there are five of them.  It’s murder to let him fight it alone!”

“Yes—­yes—­” whispered the girl, her arms tightening round him.  “Ride fast—­or put me off.  I can follow—­”

It was the first time that he had heard her voice since that last evening up at Lac Bain, many months before, and the sound of it thrilled him.

“Hold tight!” he breathed.

Like the wind they swept across the prairie and up the slope of the hill.  At the top Philip reined in.  Three or four hundred yards distant lay a thick clump of poplar trees and a thousand yards beyond that the first black escarpments of the Bad Lands.  In the space between a horseman was galloping fiercely to the west.  It was not Billinger.  With a quick movement Philip slipped the girl to the ground, and when she sprang a step back, looking up at him in white terror, he had whipped out one of his big service revolvers.

“There’s a little lake over there among those trees,” he said.  “Wait there—­until I come back!”

He raced down the slope—­not to cut off the flying horseman—­but toward the clump of poplars.  It was Billinger he was thinking of now.  The agent had fired three shots.  There had followed other shots, not Billinger’s, and after that his carbine had remained silent.  Billinger was among the poplars.  He was hurt or dead.