This fourth novel of Boothby's Dr. Nikola series reveals that Nikola has discovered all of the facts necessary to extend a human being's life. He has studied science and magic secrets of Tibetan monks. He explains: "It has been a long and tedious search, but such labour only makes success the sweeter. The machinery is now prepared; all that remains is to fit the various parts together. In six months' time, if all goes well, I will have a man walking upon this earth who, under certain conditions, shall live a thousand years."
To assist him, he hires a destitute young physician, who explains his predicament: "As ill luck would have it, however, I had got into the wrong set, and before I had been two years in the hospital was over head and ears in such a quagmire of debt and difficulties that it looked as if nothing but an absolute miracle could serve to extricate me." That miracle seems to have come to him in the person of Dr. Nikola.
The nefarious and wealthy Nikola has purchased a remote castle in the north of England, where the seclusion will allow him and his new assistant and Nikola's deaf-mute malformed Chinese servant to conduct his grand experiment on a human subject.