It was daylight before the building was cleared by the aid of high-pressure air-hoses and chemical precipitants. Except that his silver was tarnished black, and every window glass and mirror covered with a yellow deposit, little harm had been done. A musty odour pervaded the flat in spite of the open windows, but later came the morning breeze to dispel the last trace of this malodorous souvenir of the attempt. Together the two men made a search of the rooms to discover the manner in which the gas was introduced. “Through that open fireplace,” Elk pointed. “The gas is heavier than air, and could be poured down the chimney as easily as pouring water.” A search of the flat roof satisfied him that his theory was right. They found ten large glass cylinders and a long rope, to which a wicker cradle was attached. Moreover, one of the chimney-pots (easily reached from the roof) was scratched and discoloured. “The operator came into the building when the porter was busy—working the lift probably. He made his way to the roof, carrying the rope and the basket. Somebody in the street fixed the cylinders in the basket, which the man hauled to the roof one by one. It was dead easy, but ingenious. They must have made a pretty careful survey beforehand, or they wouldn’t have known which chimney led to your room.” They returned to the flat, and for once Joshua Broad was serious. “Fortunately, my servant is on a holiday,” he said, “or he would have been in heaven!” “I hope so,” responded Elk piously. The sun was tipping the roofs of the houses when he finally left, a sleepy and a baffled man. He heard the sound of boisterous voices before he reached the vestibule. A big car stood at the entrance of the flats, and, seated at the wheel, was a young man in evening dress. By him sat Lew Brady, and on the pavement was a girl in evening finery. “A jolly evening, eh, Lola! When I get going, I’m a mover, eh?” Ray Bennett’s voice was thick and unsteady. He had been drinking—was within measurable distance of being drunk. With a yell he recognized the detective as he came into the street. “Why, it’s old Elk—the Elk of Elks! Greetings, most noble copper! Lola, meet Elky of Elksburg, the Sherlock of Fact, the Sleuth——” “Shut up!” hissed the savage-voiced Lew Brady in his ear, but Ray was in too exalted a mood to be silenced. “Where’s the priceless Gordon?—say, Elk, watch Gordon! Look after poor old Gordon—my sister’s very much attached to Gordon.” “Fine car, Mr. Bennett,” said Elk, regarding the machine thoughtfully. “Present from your father?” The mention of his father’s name seemed to sober the young man. “No, it isn’t,” he snapped, “it belongs to a friend. ’Night, Lola.” He pumped at the starter, missed picking up, and stamped again. “S’long, Elk!” With a jerk the car started, and Elk watched it out of sight. “That young fellow is certainly in danger of knocking his nut against the moon,” he said. “Had a good time, Lola?” “Yes—why?”