When the king-to-be of Ruritania is kidnapped on the eve of his coronation, an English gentleman must assume the monarch's identity to prevent a political coup. Rudolf Rassendyll, a vacationing Englishman with a striking physical resemblance to King Rudolf V, finds himself thrust into a high-stakes deception to preserve the throne. He must navigate the treacherous court politics of Ruritania while evading the machinations of the king's ambitious brother, Black Michael, and the dangerous swordsman Rupert of Hentzau. The narrative unfolds through a first-person perspective, emphasizing the protagonist's internal conflict between his duty to the crown and his growing affection for Princess Flavia. The story operates under strict temporal constraints, as the impostor must maintain the ruse until the true king can be rescued.

Readers frequently highlight the novel as a foundational text for the Ruritanian romance genre, noting its influence on subsequent adventure literature. Discussion often centers on the brisk pacing and the clever use of the doppelgänger trope to drive the narrative tension. Critics observe that while the prose reflects the stylistic conventions of the late nineteenth century, the core conflict remains accessible and engaging for modern audiences. The balance between the swashbuckling action and the restrained romantic elements is often cited as a primary reason for the book's enduring popularity. Many readers appreciate how the author maintains a consistent tone of urgency throughout the protagonist's precarious tenure as a false king.