The animal was nervous.  He started and quivered at the unaccustomed sound.  But in a moment or two he responded to Burke’s insistence, and went down the sloping ground that led to the seething water.

Burke guided him with an unerring hand, holding him up firmly, for the way was difficult and uneven.  A vivid flash of lightning gave him his direction, and by it he saw a marvellous picture.  The spruit had become a wide, dashing river.  The swirl and rush of the current sounded like a sea at high tide.  The flood spread like an estuary over the veldt on the farther side, and he saw that the bank nearest to him was brimming.

The picture was gone in a moment, but it was registered indelibly upon his brain.  And the hut—­Guy’s hut—­was scarcely more than twenty yards from that swirling river which was rising with every second.

“He can’t be there,” he said aloud.  But yet he knew that he could not turn back till he had satisfied himself on this point.  So, with a word of encouragement to Diamond, he splashed onwards.

Again the lightning flared torchlike through the gloom, but the thunder of the torrent drowned the thunder overhead.  He was nearing the hut now, and found that in places the rain had so beaten down the sandy surface of the ground that it sank and yielded like a quagmire.  He knew that it was only a matter of minutes—­possibly seconds—­before the crumbling bank above the stream gave way.

He was close to the hut now, though still he assured himself that the place was empty.  The roar of the water was deafening, seeming to numb the senses.  He never knew afterwards whether a light suddenly kindled as he drew near behind the canvas that screened the hut-window, or if it had been there all along and the leaping elusive lightning had blinded him to it.  But the light was there before him as he reached the place, and in a moment the knowledge flashed upon him beyond all questioning that he had not come upon a vain quest.

He knew also with that menacing roar below him and the streaming rain around that there was not a moment to be lost.  He swung himself from Diamond’s back and secured the bridle to a projecting piece of wood at the back of the hut.  Then, floundering and slipping at every step, he made his way round to the door.

He groped for some seconds before he found it.  It was closed and he knew that there was no handle on the outside.  He battered upon it with his fist, shouting Guy’s name.

There came no answer to his summons, but the sound of the water seemed to swell in volume, filling the night.  It drove him to a fierce impatience.  If he had not seen the light he would scarcely have taken the risk.  None but a fool would have remained in such a death-trap.  But the presence of the light forced him on.  He could not leave without satisfying himself.  He set his shoulder against the closed door and flung the full weight of his body into one stupendous effort to force an entrance.