The scene opens in the pretty little Cornish fishing village of Rederring, showing the harbour and Rose Maybud's cottage. The village possesses an endowed corps of professional bridesmaids, who are languishing in idleness, there having been no weddings  for at least six months. The village beauty, Rose, will have none  of her many suitors, and, in desperation, the Bridesmaids, fearful of losing their endowment, endeavour to persuade Dame Hannah, Rose's Aunt, to marry old Adam, Robin Oakapple's faithful servant.

Hannah is, however, pledged to eternal maidenhood. Years ago, she was betrothed to a youth who woo'd her under an assumed name, but on the day when they should have been married, she discovers that he was no other than Sir Roderic Murgatroyd, one of an accursed race. She tells the girls how his ancestor, Sir Rupert Murgatroyd, employed his time in persecuting witches, and that one of his victims, in mortal agony at the stake, laid this curse on him: "Each lord of Ruddigore, despite his best endeavor, shall do one crime, or more, once every day, for ever." The penalty for defying the curse is death by

torture on the day the crimes cease, and each lord of Ruddigore has so died.

Hannah chides Rose for not returning the love of "some gallant youth," and Rose explains that her difficulty is that the youths of the village are bashful, and it would not be becoming for her to make advances. Rose is a foundling, and bases her ideals on a book of etiquette which, with a change of baby-linen, were her only possessions when she was discovered in a plated dish-cover suspended to the knocker of the workhouse door.

Robin enters and would fain consult Rose on the predicament of a friend who is in love with a maid,
but is too diffident to tell her. Rose similarly wishes to ask his advice as to her friend, and they "consult" accordingly in a charming duet, without, however, mending matters.

Robin Oakapple is really Sir Ruthven Murgatroyd, but in horror at the prospect of inheriting the title and the curse, he had fled his home and taken an assumed name. His younger brother Despard, believing him to be dead, had succeeded to the title. Old Adam enters and informs Robin that his foster-brother Richard is home from sea. This news is quickly followed by the entry of Richard himself. He kisses all the girls, spins them the yarn of the "Bold Mounseer," and dances a Hornpipe as an appropriate climax.

Dick and Robin exchange greetings, and Robin, on being upbraided for being sad, tells his foster-brother of his love for Rose, and of the shyness that prevents him from declaring it. Richard consults "the

dictates of his heart," and his heart tells him to speak up for his friend. Robin is overjoyed and sings a song, the burden of which is that, "If you wish in the world to advance . . . you must stir it and stump it, and blow your own trumpet."

Dick goes off on his self-imposed mission, but no sooner does he see Rose than his heart "dictates" once again, and says: "This is the very lass for you, Dick." So he forgets Robin, and makes love, very successfully, on his own account.

Robin enters with the Bridesmaids, and is astounded at the unexpected turn events have taken. Still, he has sworn to stand up for Dick through thick and thin. Therefore, while pretending to agree, he "gets his own back" by making many disquieting insinuations regarding the less respectable aspects of a sailor's life. This clever move turns the tables on Richard, and Rose forsakes him for Robin.

A new character is introduced -- Mad Margaret -- whose wits have been crazed by the cruel treatment of Sir Despard Murgatroyd -- the "Bad Baronet." She is actually trying to find Rose Maybud, of whom she is jealous, having heard that Sir Despard intends to carry her off as one of his daily "crimes." Rose tells her, however, that she need not fear, as she (Rose) is pledged to another. Despard Murgatroyd and his following of "Bucks" and "Blades" now appear. They are welcomed by the Bridesmaids, who are tired of village swains, and are delighted with the swaggering newcomers in their gorgeous military uniforms.

Despard bewails his lot, as one who, being really thoroughly good, is condemned to be thoroughly bad. He tries to balance his account of evil and good by getting his crime over the first thing in the morning, and then doing good for the rest of the day. For example, in the morning he steals a child, and then builds an orphan asylum.

Richard enters, and to pay off his score against Robin, he reveals his secret to Despard, who is overjoyed to learn that he is not the real heir, but that his elder brother is still living. They determine to act without delay, for Rose and Robin, with the Bridesmaids, have entered for the wedding ceremony. A lovely Madrigal is sung, followed by a Gavotte, and the procession is about to start for the church, when Despard enters, and challenges Robin, claiming him as his elder brother Sir Ruthven Murgatroyd, rightful heir to the Baronetcy of Ruddigore. He cannot deny the fact, and Rose, in spite of Richard's blandishments, forsakes him, and offers herself to Despard. This offer is refused, for Despard, once again virtuous, keeps his vow to Margaret. Rose returns to Richard, and Robin, now  the "Bad Baronet," falls senseless to the ground.