The Emerald Isle; or, The Caves of Carrig-Cleena, is a two-act comic opera, with music by Arthur Sullivan and Edward German, and a libretto by Basil Hood. The plot concerns the efforts of an Irish patriot to resist the oppressive "re-education" programme of the English, which has robbed the Irish of their cultural heritage. A quirky "Professor of Elocution" who is hired by the English to continue this "re-education" of the Irish switches sides to help the Irish defend their culture. Romantic complications cause a confrontation between the Irish patriots and the superstitious English at the supposedly haunted caves of Carric-Cleena, and disguises are employed to hold the English off; but the professor ultimately comes up with a solution that works out happily for all.