The outlaw had disappeared in the black edge of the Bad Lands when Philip dashed up out of the dip into the plain.  There was only one break ahead of him, and toward this he urged his horse.  In the entrance to the break there was another sandy but waterless dip, and across this trailed the hoof-prints of the outlaws’ mounts, two at a walk—­one at a gallop.  At one time, ages before, the break had been the outlet of a stream pouring itself out between jagged and cavernous walls of rock from the black heart of the upheaved country within.  Now the bed of it was strewn with broken trap and masses of boulders, cracked and dried by centuries of blistering sun.

Philip’s heart beat a little faster as he urged his horse ahead, and not for an instant did his cocked revolver drop from its guard over the mare’s ears.  He knew, if he overtook the outlaws in retreat, that there would be a fight, and that it would be three against one.  That was what he hoped for.  It was an ambush that he dreaded.  He realized that if the outlaws stopped and waited for him he would be at a terrible disadvantage.  In open fight he was confident His prairie-bred mount took the rough trail at a swift canter, evading the boulders and knife-edged trap in the same guarded manner that she galloped over prairie-dog and badger holes out upon the plain.  Twice in the ten minutes that followed their entrance into the chasm Philip saw movement ahead of him, and each time his revolver leaped to it.  Once it was a wolf, again the swiftly moving shadow of an eagle sweeping with spread wings between him and the sun.  He watched every concealment as he approached and half swung in his saddle in passing, ready to fire.

A quick turn in the creek bed, where the rock walls hugged in close, and his mare planted her forefeet with a suddenness that nearly sent him over her head.  Directly in their path, struggling to rise from among the rocks, was a riderless horse.  Two hundred yards beyond a man on foot was running swiftly up the chasm, and a pistol shot beyond him two others on horseback had turned and were waiting.

“Lord, if I had Billinger’s gun now!” groaned Philip.

At the sound of his voice and the pressure of his heels in her flank the mare vaulted over the animal in their path.  The clatter of pursuing hoofs stopped the runner for an instant, and in that same instant Philip halted and rose in his stirrups to fire.  As his finger pressed the trigger there came to his ears a thrilling sound from behind him—­the sharp galloping beat of steel upon rock!  Billinger was coming—­Billinger, with his broken leg and his carbine!

He could have shouted for joy as he fired.

Once—­twice, and the outlaw was speeding ahead of him again, unhurt.  A third shot and the man stumbled among the rocks and disappeared.  There was no movement toward retreat on the part of the mounted men, and Philip listened as he slipped in fresh cartridges.  His horse was panting; he could hear the excited and joyous tumult of his own heart-but above it all he heard the steady beat, beat, beat of those approaching hoofs!.  Billinger would be there soon—­in time to use his carbine at a deadly rate, while he got into closer quarters with his revolver.  God bless Billinger—­and his broken leg!