Guy Boothby's fourth novel of five about the svelte mysterious anti-hero Dr Nikola sees him progress further on his search for immortality. Here we find him deep in the wilds of Northumbria conducting an experiment of longevity and restoration of youth with another somewhat naive assistant. He is pursued by his Chinese enemies who will stop at nothing to achieve his demise. In this novel he displays a slight hint of emotion regarding his assistant's love affair with a beautiful Spaniard. Once again you are left wondering whether you like him or detest him, his relentless pursuit of arcane knowledge at all cost continues.