irn, with aching head and a growing sensation of nausea,
paused on the landing, looking down into the court below. He could not
disguise from himself that he felt ill, not nervously ill as in
London, but physically sick. This superheated air was difficult to
breathe; it seemed to rise in waves from below.

Then, from a weary glancing at the figures beneath him, his attitude
changed to one of tense watching.

A man, wearing the crocodile mask of Set, stood by a huge urn
containing a palm, looking up to the landing!

Cairn's weakness left him, and in its place came an indescribable
anger, a longing to drive his fist into that grinning mask. He turned
and ran lightly down the stairs, conscious of a sudden glow of energy.
Reaching the floor, he saw the mask making across the hall, in the
direction of the outer door. As rapidly as possible, for he could not
run, without attracting undesirable attention, Cairn followed. The
figure of Set passed out on to the terrace, but when Cairn in turn
swung open the door, his quarry had vanished.

Then, in an _arabiyeh_ just driving off, he detected the hideous mask.
Hatless as he was, he ran down the steps and threw himself into
another. The carriage-controller was in attendance, and Cairn rapidly
told him to instruct the driver to follow the _arabiyeh_ which had
just left. The man lashed up his horses, turned the carriage, and went
galloping on after the retreating figure. Past the Esbekiya Gardens
they went, through several narrow streets, and on to the quarter of
the Muski. Time after time he thought he had lost the carriage ahead,
but his own driver's knowledge of the tortuous streets enabled him
always to overtake it again. They went rocking along lanes so narrow
that with outstretched arms one could almost have touched the walls on
either side; past empty shops and unlighted houses. Cairn had not the
remotest idea of his whereabouts, save that he was evidently in the
district of the bazaars. A right-angled corner was abruptly
negotiated--and there, ahead of him, stood the pursued vehicle! The
driver was turning his horses around, to return; his fare was
disappearing from sight into the black shadows of a narrow alley on
the left.

Cairn leaped from the _arabiyeh_, shouting to the man to wait, and
went dashing down the sloping lane after the retreating figure. A sort
of blind fury possessed him, but he never paused to analyse it, never
asked himself by what right he pursued t