* * * * *

It had been some time since they had seen the dots, and now the road ahead of them, like the former path they had abandoned, was turning more and more to the left, winding in and out the low and broken foothills, and as they followed its course with increasing security, Billy began to tell himself that their fears had been unfounded and the alarming horsemen were merely following their own route south.

And then he heard a whistle.

A prescience of danger shot through him.  His fears returned a hundredfold.  Sharply he scanned the way about them, but nothing was in sight.  The whistle was not repeated; he could have imagined that he dreamed it.  An utter stillness possessed the wilderness.

And then around the corner of a jutting rock ahead of them a horseman trotted, a big black man on a gray horse, and reined in, waiting, facing them.  Arlee gave a choking cry.

“The eunuch!” she gasped out.

Behind them Billy flung a lightning glance, and over the heads of the dunes two more riders appeared, converging down upon them from the rear.  Three in sight—­how many more behind the rocks?

Desperately Billy gripped his bridle rope, and with a wrenching pull and a whack of his guiding stick he turned his camel sharply to the left, snatching at Arlee’s bridle rope as the beasts bumped against each other in their surprise.

“Quick—­this way,” Billy commanded, and with the left hand clutching the girl’s rope, with the right he wielded the stick furiously.  Out over the sand both camels plunged, goaded into wild speed by such violent measures, and a cheated yell broke from the horsemen and the outcries of pursuit.

While rage at such unreason lasted the camels went like mad, but such speed could not be for long.  They had been hard ridden for two days and they were nearly spent.  The horsemen behind had drawn together and hung on their trail like three hounds, riding cautiously in the rear, but easily keeping the distance.  It occurred to Billy that these pursuers could have changed horses on the way, and must inevitably tire them out.  And then?

On and on he beat his poor beasts, racing toward the hills that, just ahead of them, rose sharply from the broken ground, seeking among them some fortress of rocks for a defiant stand.

A tug on the bridle rope nearly jerked it from his hand.  Arlee’s camel had stumbled; the poor thing was lurching wearily.

“He can’t go—­any more,” the girl cried out pitifully.  “He—­he’s sobbing.  Don’t beat him—­I won’t have him beaten!”

“We must get there,” he called back, waving at the cliff-like rocks.

“Then go—­on foot.  I could—­run faster.”

“No, you couldn’t,” he shouted fiercely back.

She flared.  “Don’t you hit him again!”

The maddening absurdity of the quarrel in the face of hostile Africa filled Billy with the futile fury of exasperation.  He ground his teeth, glowering at her, and wound her halter rope about his smarting hand.  All his hope was concentrated upon the necessity of winning to that rocky shelter before their pursuers overtook them.  To him the camels were nothing in the face of such necessity.