Gilbert and Sullivan are widely known as one of the great British opera-writing duos of the late 19th century. Or, more accurately, the only great British opera-writing duo of the late 19th century.
Though they are credited with numerous famous works, including The Mikado and The Pirates of Penzance, it has been suggested that they only ever wrote one operetta consisting of a single song, and they merely varied the costumes and the quality of the actors from performance to performance.
The plot of this generic Gilbert and Sullivan operetta goes something like this. A dozen identical people show up on stage singing The Song (depending on the costumes used in this particular performance, the people may be young maidens, pirates, Japanese citizens, used vacuum cleaner salesmen and any of countless other stereotypes).
From among this group, person A emerges; he/she is madly in love with person B, and woefully sings The Song to attest to the fact. Person B emerges in the following scene where we discover that, alas, person B is in love with person C. Person C has, depending on the quality of the acting, has either been sentenced to death, captured by pirates, joined the local government, is a poet, or has contracted a terminal disease. As the first act closes, everyone sings The Song, lamenting just how screwed up the world can be, by which stage you're inclined to agree because you can't believe you actually paid good money for a balcony seat to see this stuff.
By the middle of the second act person D arrives, falls in love with and marries person A, who by now has given up on all hope of marrying person B... or was it person C? Person C sings The Song and by doing so is miraculously rescued, pardoned or healed, such that he/she can marry person B and everyone lives happily ever after.
After singing a final joyful chorus of The Song, that is.