Frederic, who, having completed his 21st year, is released from his apprenticeship to a band of tender-hearted pirates. He meets Mabel, the daughter of Major-General Stanley, and the two young people fall instantly in love. Frederic soon learns, however, that he was born on the 29th of February, and so, technically, he has a birthday only once each leap year. His indenture specifies that he remain apprenticed to the pirates until his "twenty-first birthday", meaning that he must serve for another 63 years. Bound by his own sense of duty, Frederic's only solace is that Mabel agrees to wait for him faithfully while he tries to find a way of breaking away from the pirates. Music by Arthur Sullivan - Book and Lyrics by W. S. Gilbert.