Helena, a spirited British chieftain's daughter, navigates the shifting political and religious landscapes of the Roman Empire while seeking a singular, enduring truth. Cast into a marriage with the future emperor Constantius, Helena finds herself displaced from her homeland and thrust into the complex, often treacherous machinery of imperial life. As she matures, she rejects the hollow philosophies and mythologies of her era, eventually finding purpose in the nascent Christian faith. The narrative follows her evolution from a horse-loving youth to a historical figure of significant religious influence, utilizing a third-person perspective that balances historical scope with intimate character observation.

Readers and critics frequently note that this work stands apart from the author's more famous satirical novels due to its earnest, albeit still witty, exploration of faith. Discussion often centers on the author's personal attachment to the book, with many identifying it as a reflection of his own spiritual convictions. The prose is described as lean and precise, effectively capturing the atmosphere of the declining Roman world without succumbing to excessive ornamentation. Critics highlight the protagonist's grounded, pragmatic nature as a counterpoint to the grandiosity of the imperial setting, making the narrative feel both intimate and expansive. The book remains a subject of debate regarding its historical accuracy versus its theological intent, yet it is widely regarded as a significant entry in the author's bibliography.