"The Pirates of Penzance" spins a tale full of humor and whimsy, highlighting the peculiar journey of Frederic, a loyal yet misguided pirate apprentice. When Frederic's 21st birthday marks the supposed end of his indenture, revelations and misunderstandings lead to a series of intriguing encounters and comic twists. The story delves into themes of duty, identity, and the absurdity of rigid adherence to rules.

The Apprentice's Liberation

Frederic, on the cusp of freedom from his apprenticeship as a pirate, looks forward to leaving behind the life of a buccaneer. The pirate king, with a sense of pride, anticipates Frederic's continued involvement with the crew, unaware of Frederic's true intentions. Frederic, driven by a strong sense of duty, intends to part ways and even plans to eradicate the pirates. Despite their affection for Frederic, the pirates understand his resolve, acknowledging their own shortcomings as buccaneers.

An Honest Confession and New Resolve

Ruth, a maid in the pirate band, reveals her past mistake of apprenticing Frederic to pirates instead of a pilot due to her hearing impairment, a decision she kept secret by joining the pirates herself. Frederic, feeling responsible, vows to combat the pirates' influence, despite a personal fondness for them individually. The pirates are noted for their overly kind-hearted nature, refusing to harm orphans or weaker parties, which has led to their failure as fearsome marauders.

Ruth's Uncertain Fate

Upon Frederic’s departure, Ruth grapples with her future, as Frederic contemplates taking her along. Uncertain of her appeal, Frederic seeks validation from the pirate king, who diplomatically praises her beauty. However, Frederic remains skeptical until the arrival of a group of young maidens starkly contrasts Ruth's charms, leading to Ruth's confession of having misled him about her age and appearance.

A Chance Encounter

As Frederic encounters a group of beautiful maidens, Ruth admits defeat, acknowledging her deception. Frederic, captivated by the new arrivals, meets Mabel, one of the sisters, who empathizes with his plight and offers her affection. Her sisters, Kate, Edith, and Isabel, question whether Mabel would have been so dutiful if Frederic were less attractive.

Unexpected Tensions

Frederic warns the maidens of the pirates' approach just as the pirate king leads his band to capture them. Their father, Major General Stanley, arrives just in time to confront the pirates, declaring his vast but non-military knowledge. Desperate to save his daughters, he claims to be an orphan, exploiting the pirates' weakness for orphans, prompting them to reluctantly release the sisters.

The General's Dilemma

Back at his ancestral home, Major General Stanley wrestles with guilt over his deceit. Frederic comforts him, justifying the lie to protect his daughters. As midnight approaches, Frederic prepares to lead a police force against his former comrades, though his sense of duty holds him bound to the pirates until the last moment.

The Leap Year Twist

As the police prepare for their mission, Frederic is confronted with a shocking revelation by the pirate king and Ruth: due to his leap year birthday, he is technically only five years old and bound to the pirates until 1940. Frederic, though finding humor in the paradox, must return to the pirate fold, informed by a renewed sense of duty.

The Pursuit of Truth

Frederic, once again a pirate, feels compelled to disclose Major General Stanley's untruth about being an orphan. The pirates, eager for retribution, move to capture Stanley, leading to a confrontation with the police. Despite their initial success, the pirates are swayed by an appeal to their loyalty to Queen Victoria and eventually surrender.

A Noble Revelation

In the final turn of events, Ruth unveils the pirates' true identities as wayward noblemen. This revelation prompts forgiveness from Major General Stanley, who is moved to reconcile with the pirates, granting them his daughters' hands in marriage as they return to their former lives of nobility.