"Fire of the Immortals" is a portion of a line in a poem by Henry Wadsworth Longfellow, "Prometheus, or the Poet's Forethought". The significance of the reference is the way people set themselves up to replace God as the bringers of fire, or any other useful technological development that purports to elevate Man out of his struggle with nature. What such a quest always fails to account for, however, is a knowledge of love that is imprinted on human hearts that is indelible, and therefore can only be overcome by coercion, force, and violence in order to bring about a heaven on Earth. The book is an allegory about the proxy war between God and Satan going on every day down on Earth, set on a backdrop roughly paralleling the Wars of the Roses fought between the rival houses of Lancaster and York, and the human motivations of envy, greed, and a need for control that daily drive decisions made by people. These decisions, taken to their logical extremes, result in increased control of many by few, and piles of bodies along the way. The antidote is constant introspection and a willingness to call out evil and stand up to it, and even taking life in order to defend innocents as required. The story uses this conflict as a means of explaining why the world turned away from representative self-government by the citizenry and instead coalesced around a controlling, regimented corporate structure that sees itself as not only the guarantor and provider of material comfort, but the spiritual guide and exemplar of what a useful, efficient life really means. The human spirit is not so reworkable, however, and all it takes to thwart the worst impacts of evil motivations is enough people willing to acknowledge that humans are not gods and must not look to other humans to be the final word on what constitutes a moral life. Individuals have dignity and groups have utility, and attempting, as the controllers do, to invert this truism leads to the downside of playing with fire.
The book is also a paean to fighter pilots and the special world they inhabit that combines the most ancient killing instincts with the operation of high-tech aerial fighting machines. These sky fighters are part engineer and part high-intensity athlete, with a helpful amount of the warrior spirit of Achilles for motivation.