From afar they heard the sonorous clang of a gong. The lower edge of the first full moon of spring had just cleared the horizon. Filing down Biban ul Djinni was a caravan of camels and horses, bearing at a steady gait toward a cluster of shattered columns whose stumps towered skyward. As the light of the rising moon grew stronger, they could pick out the figure of a warder on guard in the center of a circular courtyard. "Worse and worse yet!" exclaimed Ismeddin, as the Shareef drew up beside him. "Though I more than half expected as much. About forty of those sons of Satan.... You and I might have taken those seven by surprize----" "Well, why not wait for the guard, _Hajji_?" demanded the Shareef. "Too late!" snapped Ismeddin. "You heard that gong? A warning signal. That caravan arrived just in time for the sacrifice. You and I must stop it." "_Wallah!_ But the odds are great.... Still----" The Shareef drew his scimitar. "After my own heart, _saidi_!" exclaimed the darvish. "But rash. Let them first get under ground----" "But how about the sentry?" demanded the Shareef. "He'll give the alarm." "On the contrary, uncle. Look!" Ismeddin produced from his capacious wallet a small, glittering object: the effigy of a peacock carved of silver. "Malik Taûs! The damnation of Allah upon him!" exclaimed the Shareef as he recognized the symbol of the devil-worshipers. "Follow me!" commanded Ismeddin, as he spurred his weary horse down the steep side of the valley. They rode boldly now, making no attempt at concealment. The warder standing watch in the center of the ruined courtyard was taking an observation with his astrolabe, following the course of a star that flamed bloodily overhead. Then he set aside his instrument and smote a brazen gong whose golden sheen they could plainly see in the white moonlight. The solemn, vibrant note rolled dreadfully across the valley. The tall figure of doom once more turned his astrolabe on the star whose altitude he was reading. Ismeddin leaned forward in the saddle, chirping and muttering to his exhausted beast. "Allah, what a horseman!" gasped the Shareef as he saw the _asil_ mare, true to her breeding, stretch out again at a full gallop. They clattered up the broad avenue, clearing fragments of monstrous columns at a bound, Ismeddin shouting in a language unknown to the Shareef. The warder started, and turned to face them. "Hurry, _saidi_! The moment is almost here." And then: "The sign and the symbol!" Ismeddin extended the silver image of the peacock, and in response to the warder's muttered formula, replied in that same obscure tongue. The warder bowed, gestured toward the cavernous entrance to the vault, and turned to resume his observations.... The Shareef's blade flickered in the moonlight. Ismeddin seized one of the torches that flared smokily at each side of the copper image, and plunged into the depths, three steps at a time. * * * * *