Two-act comic-opera written by Gilbert and Sullivan.

Frederic has mistakenly been sent to serve a ship of friendly pirates by his hard-of-hearing nursemaid (instead of a ship's pilot) and celebrates the termination of his restrictive apprenticeship at the age of 21. But he learns that his apprenticeship must continue for the rest of his life due to a simple technicality - he was born on a leap year on 29th February and is therefore only allowed to be released upon his official 21st birthday, a few decades later.