The Invisible Death ♦ By Victor Rousseau

Through the character of Captain Richard Rennell, it tells the story of the United States government fighting against an invisible army that seeks to subjugate the entire country! With night-rays and darkness-antidote America strikes back at the terrific and destructive Invisible Empire.

Excerpt
“You speak," said Von Kettler, jeering, "as if you really believed that you had the power of life and death over me."
The Superintendent of the penitentiary frowned, yet there was something of perplexity in the look he gave the prisoner. "Von Kettler, I think it is time that you dropped this absurd pose of yours," he said, "in view of the fact that you are scheduled to die by hanging at eight o'clock to-morrow night. Your life and death are in your own hands."
Von Kettler bowed ironically. Standing in the Superintendent's presence in the uniform of the condemned cell, collarless, bare-headed, he yet seemed to dominate the other by a certain poise, breeding, nonchalance.
"Your life is offered you in consideration of your making a complete written confession of the whole ramifications of the plot against the Federal Government," the Superintendent continued.
"Rather a confession of weakness, my dear Superintendent," jeered the prisoner.

“Oh don't worry about that! The Government has unraveled a good deal of the conspiracy. It knows that you and your international associates are planning to strike at civilized government throughout the world, in the effort to restore the days of autocracy. It knows you are planning a world federation of states, based on the principles of absolutism and aristocracy. It is aware of the immense financial resources behind the movement. Also that you have obtained the use of certain scientific discoveries which you believe will aid you in your schemes."
"I was wondering," jeered the prisoner, "how soon you were coming to that."
"They didn't help you in your murderous scheme," the Superintendent thundered. "You were found in the War Office by the night watchman, rifling a safe of valuable documents. You shot him with a pistol equipped with a silencer. You shot down two more who, hearing his cries, rushed to his aid. And you attempted to stroll out of the building, apparently under the belief that you possessed mysterious power which would afford you security.