A chorus of professional bridesmaids frets that there have been no weddings lately. All of the young men want to marry Rose Maybud, the prettiest girl in the village, but are too shy to approach her. 

Dame Hannah tells the bridesmaids about the curse of Ruddigore. Centuries ago, Sir Rupert Murgatroyd, the first Baronet, had persecuted witches, and one of them had cursed all future Baronets to commit a crime every day, or perish in agony.  

Dame Hannah greets her niece, Rose, and they talk about her suitors, particularly Robin Oakapple. Unknown to them, Robin is secretly Sir Ruthven Murgatroyd, having run away years before to avoid inheriting the curse. 

Robin seeks advice from Rose about “a friend” who is in love. Rose says that she has such a friend too, but Robin is too shy to take the hint. He tells his foster-brother, Richard Dauntless that he is too shy to confess his feelings to Rose. Richard offers to speak to her on his behalf, but falls in love with Rose himself. The two enjoy a brief engagement before Rose breaks it off and accepts Robin instead.  

Mad Margaret, desperately in love with the current “Bad Baronet” Sir Despard Murgatroyd, enters. She has heard that Sir Despard intends to carry Rose off as one of his daily crimes and is worried, but Rose reassures her.  

Sir Despard enters. He muses that, although he is forced to commit a crime every day, he does so early and then does good works for the rest of the day. Richard approaches and reveals that Despard’s elder brother Ruthven is actually alive and living as ‘Robin Oakapple’. Despard is elated and shortly interrupts the wedding of Rose and Robin, revealing Robin’s true identity and insisting his accept his title as the Bad Baronet. Sir Despard takes up with his old love Mad Margaret, and a horrified Rose accepts Richard.

At Ruddigore Castle, Robin (now Sir Ruthven) tries to get to grips with being a bad baronet.  

The ghosts of his ancestors are unimpressed with the feebleness of his crimes, and Robin’s uncle, the late Sir Roderic Murgatroyd, orders him to do something drastic and “carry off a lady” immediately, or die in agony.  In panic, Robin orders Adam to go to the village and abduct any lady.  

Despard, now reformed and married to Mad Margaret, comes to the castle and urges Robin to renounce his life of crime. Robin resolves to defy his ancestors.  

Meanwhile, Adam has chosen to abduct Dame Hannah, who proves very unwilling, and Robin cries out for his uncle’s protection. 

Robin argues that, under the terms of the curse, a Baronet of Ruddigore can die only by refusing to commit a daily crime. Refusing is therefore equal to suicide, “but suicide is, itself, a crime”. Thus, he reasons, his predecessors ought never to have died at all! The ghost of Sir Roderic follows this logic and agrees, freeing Robin of the curse.  

Rose once again drops Richard and resumes her engagement to Robin.