The famous Pirates of Penzance approach their secret hideout.
The pirate King thanks his apprentice, Fredric, for his years of loyal service.
Frederic's nurse, Ruth, explains to him that she accidently apprenticed him to a PIRATE, when she was meant to apprentice him to a PILOT.
Frederic shakes hands with the Pirate King and says farewell. The pirates leave him all alone.
Some beautiful ladies walk along the beach. Frederic hides behind a rock and sees them, the first females (besides Ruth) he has ever seen. He likes Mabel, with the white dress.
Frederic comes over to Mabel.
The other pirates return.
They meet the other ladies and decide to capture them.
Then Major General Stanley, the girls' father, arrives. He is the very model of a modern Major General. He sings an amusing and linguistically gymnastical song involving Waterloo, differential calculus and the square of the hypotenuse.
General Stanley talks to the pirate king. Knowing that the Pirates of Penzance are all orphans, Stanley falsely claims to be an orphan himself.
Since the pirates identify with General Stanley (being orphans themselves) they feel sorry for him, and so the pirates set him and his daughters free.
That night, at his estate, General Stanley feels bad that he lied to the pirates about being an orphan.
Frederic feels honor-bound to hunt down the pirates (since they are, after all, pirates) and he enlists the help of three police officers.
The officers go off while Frederic stays behind. Then the Pirate King and Ruth arrive.
They explain to Frederic a most amusing paradox: his apprenticeship lasts until his 21st birthday. And since he was born on February 29th, he has actually only had 5 birthdays so far. So technically, he is still apprenticed to the pirates.
Unfortunately, Frederic is honor-bound to return to the pirates. Mabel promises to wait for him.
The police agree, reluctantly, to hunt the pirates without Frederic.
But when Frederic tells the pirates that General Stanley lied, they sneak in to get revenge. The police officers all hide.
The pirates capture General Stanley and threaten to kill him.
His daughters plead for his life.
At last, the police come out of hiding and fight the pirates.
The police are quickly overcome by the pirates.
The police demand that the pirates surrender in the name of the Queen. The pirates give in. Ruth explains that the pirates are all noblemen.
General Stanley invites the pirates to return to society and marry his daughters.