My brain whirling I gave up the struggle after one more ineffectual attempt to free myself and resigned myself to my fate.
Horror froze the blood in my veins as I gazed in agony first at Thelma, helpless and unconscious in her loveliness, and then at that innocent-looking toy balloon, charged with the deadliest menace, hanging only a few inches above the flickering candle. To my distorted imagination it appeared to be swelling monstrously and hideously. I felt myself stupidly wondering how much larger it would grow until it split and let loose a flood of fire in that silent room.
I realized the devilish ingenuity of the scheme. It was clear that once the balloon burst and the volatile spirit became ignited, the furniture and hangings of the room would burn with terrific violence. The fire could not be seen through the shuttered windows until practically the entire house was ablaze, even if at that late hour a chance passerby should come along. And before help could possibly reach the spot, the house would be a furnace. Every trace of the cause of the fire would be consumed: only our bodies, charred beyond all possible identification, would be found beneath the ruins. Our fate would remain unsolved and the fire would be relegated to the ever-growing list of London’s unsolved mysteries. I found myself dully speculating as to the insurance, realizing that the owner of the house would be duly recompensed, and that the assassin whom I had never even suspected would go scot free.
And above all, even in those swiftly flying moments, I still speculated as to Humphreys’ possible motive in a plot which, I was now convinced, must have been originally formed amid the snows of Switzerland—a plot between the mysterious doctor and the cosmopolitan financier who had posed as my friend. How could Hartley Humphreys, reputed millionaire, benefit by the extinction of two such humble lives as Thelma’s and my own? Murder is seldom or never motiveless, except it be committed by the homicidal maniac. Was Humphreys really insane or was he a cool, calculating, ruthless criminal, working out to its logical end some plan to which I had not the key?
At any rate, so far as we were concerned, we were faced by instant peril. Humphreys had laid his plans well. We had no possible loophole for escape. I was pinned and could not budge from the wall against which I was held. If I had been handcuffed—and handcuffs can be bought of many gun-makers in London—they would have remained as tell-tale evidence amid the débris of the fire. That length of rope showed how cleverly the plot had been devised so that all evidence of the murders would be effaced by the roaring flames.
By the faint light of the candle I could scarcely discern more than the marble face of the girl I had grown to love. My eyes ever and anon wandered to that yellow globe suspended above the table.
At any second it might burst. Then the flames would run rioting through the room and in a moment we should be enveloped.
Again I tried to shout for assistance.
All was silent. The candle flickered and then again grew brighter.
“Thelma!” I shrieked in my agony, but my voice was only a whisper.