Part 1. The Departure
An intruder has been spotted at night on the grounds of Ravenswood Castle. Norman, the captain of the guard, sends his men off in search of the stranger. Lord Henry tells Raymond Bidebent, his sister Lucia’s chaplain and tutor, that his family’s fortunes are in danger. Edgar Ravenswood, the son of the castle’s previous owner, can maneuver Henry out of his property and gain back his political influence. Only the arranged marriage of his sister, Lucia, can save them. However, Lucia does not want to accept the marriage. Raymond reminds Henry that the girl is still mourning the death of her mother. But Norman reveals that Lucia is concealing a great love for a mysterious stranger who saved her from the attack of a raging bull. She meets with him in secret. The returning men reveal the identity of the man whom Lucia is secretly meeting each day – it is Edgar Ravenswood. Henry is furious.
Lucia is waiting by an old fountain with her maid Alice for a secret meeting with Edgar. Lucia is frightened by the legend of the fountain: a woman was murdered here by an insanely jealous member of the Ravenswood family. The ghost of the murdered woman has recently appeared to her, beckoning Lucia to follow her. When the ghost disappeared, the water in the fountain turned red with blood.
Edgar appears. He explains that he must leave Scotland and go to France on a political mission. Before he leaves, Edgar wants to ask Henry for Lucia's hand. Terrified of her brother’s reaction, Lucia asks Edgar to keep their love a secret. Edgar tells Lucia of his undying hatred of the Ashtons, how he swore a vow of vengeance upon her family. But now the vow is destroyed by love. The young lovers solemnly pledge their troth by exchanging rings.
Part 2. The Marriage Contract
Guests are arriving at the wedding of Lucia and Lord Arthur Bucklaw. Henry is still worried that Lucia will not accept the groom. Norman reassures him: all the letters that Edgar has written during his long absence have been seized and replaced with artful forgeries in which Edgar confesses that he has fallen in love with another woman. As his sister enters, Henry chastises her for being so melancholy on the day of her wedding. She replies that his cruelty is the cause of her grief. Henry tries to persuade his sister to forget her illicit love and hands her a forged letter. Lucia is shattered: all her tears, her hopes, and her yearning have been wasted on an unfaithful man. At Raymondʼs fervent pleading, the exhausted Lucia finally gives in and agrees to marriage.
The guests enthusiastically greet Lord Arthur Bucklaw. Arthur assures Henry of his friendship and promises his support. He asks, however, wherever the rumours about Edgar Ravenswood being in love with Lucia are true. Lucia appears.
Lucia is showed into the room with her marriage contract on the table. There is commotion outside: it is Edgar, who has now returned from France. The men draw their swords. Lucia falls unconscious. Raymond intercedes and shows Edgar the contract with Lucia’s signature. Lucia tearfully confesses that the signature is hers. Enraged, Edgar returns his ring and demands that she returns hers.
A heavy thunderstorm rages outside. Henry visits Edgar at the Wolf's Crag. He challenges Edgar to a duel. They agree to fight in the morning by the graveyard of the Ravenswoods. Scene two.
The guests continue to celebrate the wedding. Raymond breaks up the festivities with terrible news: Lucia has gone mad and stabbed Arthur to death. The crazed Lucia, her nightgown stained with blood, appears in the hall. She thinks that she is once more in the garden, on the way to meet her beloved Edgar. However, her happiness quickly turns into horror as she sees the ghost. Lucia begs Edgar to hide and leads him to the altar decorated with roses. She sees a church, where she is married to Edgar, not Arthur. Lucia collapses.
Edgar is at the graveyard of the Ravenswoods, where he is to duel Henry. He laments that he has to live without Lucia and hopes that his duel with Henry will end his own life. Guests coming from the Castle tell him that Lucia has gone mad and is dying. The bell tolls.