The Pirates of Penzance recap

Frederic completes an apprenticeship to the Pirates of Penzance, an error caused when his nurse Ruth confused a pirate with a ship's pilot. He leaves intending to destroy the band, rejects Ruth as a bride, and falls in love with Mabel, daughter of Major-General Stanley. When the pirates seize the other daughters, Stanley escapes by claiming to be an orphan, since the tenderhearted band never attacks orphans. Frederic and Mabel plan to marry while the police prepare to arrest the pirates. Ruth and the Pirate King then reveal that Frederic was born on leap day: his contract binds him until his twenty-first birthday, not merely his twenty-first year, so duty compels him to rejoin them. He also reveals Stanley's lie. The pirates defeat the police but surrender when commanded in Queen Victoria's name. Ruth announces that they are noblemen who went astray, Stanley accepts them as husbands for his daughters, and Frederic and Mabel are reconciled.

Frederic reaches the end of his apprenticeship to the Pirates of Penzance, having been assigned to them because his nurse Ruth misheard an instruction to place him with a ship's pilot. Although fond of the pirates, his strict devotion to duty means that once free he intends to help exterminate them. Ruth, his only female companion since childhood, hopes he will marry her, but the arrival of Major-General Stanley's daughters makes him recognize that she has misrepresented her attractions. Mabel accepts Frederic despite his upbringing, and they fall in love. The pirates capture the other daughters and propose immediate marriages. Major-General Stanley stops them by claiming to be an orphan, knowing that the band releases anyone who makes that claim. The pirates withdraw, leaving Frederic and Mabel engaged and the general troubled by the lie that saved his family.

At the general's estate, Frederic organizes a police expedition against the pirates while Mabel promises to wait for him. The Pirate King and Ruth arrive with a discovery about Frederic's contract: because he was born on February 29, he has experienced only a handful of birthdays, and the apprenticeship lasts until his twenty-first birthday rather than until age twenty-one. Frederic's sense of duty obliges him to return to the band. The same principle makes him reveal that Major-General Stanley is not an orphan. The pirates plan revenge and attack, overcoming the hesitant police. When the Sergeant orders them to yield in Queen Victoria's name, however, their patriotism makes them surrender. Ruth then explains that the pirates are noblemen who have gone astray. Their birth transforms Stanley's view of them, and he permits them to marry his daughters. Frederic and Mabel are reunited as the conflict ends in a general social restoration rather than imprisonment.

Frederic's leap-day birthday binds him to the pirates for decades more, and his rigid sense of duty forces him to rejoin them and disclose Major-General Stanley's lie about being an orphan. The pirates attack the general's estate, overpower the police, and seize the household. The Sergeant then calls upon them to submit in Queen Victoria's name. Their loyalty to the Crown proves stronger than their resistance, so they surrender. Ruth supplies the final change in status by revealing that the pirates are not common criminals by birth but noblemen who have gone astray. Major-General Stanley immediately regards them as acceptable sons-in-law and gives them his daughters. The social and legal obstacles collapse together: the pirates regain rank, the daughters receive husbands, and Frederic can be united with Mabel without betraying the duty that has directed his decisions. The resolution converts the threatened punishment of pirates into a general reconciliation based on birth, patriotism, and the same convenient literalism that created the conflict.