xclaimed Jack aloud. "What can they be doing? I
suppose they are going to relieve the pickets, or the guards over the
guns. But it is an unusual time. Of course I know that the colonials
take their turn, but they are generally marched up to change guard just
before the evening parade. I'll just watch, and at the same time keep
out of sight, for they will pass close by me."

He promptly entered his tent, and, lying full-length on the ground,
lifted the flap, and again watched the volunteers through his
field-glasses. Soon they were close at hand, and though it was already
getting dusk, something about the figure of the officer caught his
notice, and that, combined with the peculiar manner in which he threw
out his feet, set Jack wondering who he was.

"I'm sure I've had something to do with that fellow before," he
muttered. "Who can he be?"

Jack puzzled his brains, but could not solve the problem, and was on the
point of giving it up in disgust when the merest chance disclosed it to
him. There was a sentry standing in front of an iron hut used as the
paymaster's office, and as the volunteers got opposite him, and just in
front of Jack, the watchful man hailed them and shouted: "Halt! who goes
there?" saluting the party at the same moment by shouldering his rifle.

He was evidently a young soldier, and eager to be considered wide-awake,
or else he would have remembered that it was already dusk and no salute
was required. Still it served Jack's purpose, for a second later "Eyes
right!" and "Gun picket!" was shouted out in a voice which made him
tingle from head to foot and tremble with excitement, for the voice and
the figure together told him that it was none other than Piet Maartens,
his old enemy, who had so nearly proved the death of him in the
Transvaal magazine.

"Good heavens!" Jack exclaimed in astonishment. "What does it mean?
Can he have come over to our side to fight against the Boers? No,
that's impossible. He must be a spy, and, by George! those other men
with him must belong to the enemy too."

Jack sprang to his feet and gazed after the squad of volunteers. Then
he thought for a few moments, and, having determined what to do, he
dived into the tent again, and, snatching up his rifle, ran across to
call Guy Richardson.

"Quick, Guy!" he said, pushing his head into the hut in which Guy and
Mr Hunter lived. "Come out here! I want you both! Bring your
rifles!"

An instant later all we