During the overture, a chorus behind the show curtain explains that two weary hunters have lost their way in the Highlands of Scotland (Once in the Highlands)
In the forest, at about five in the morning, we meet the hunters: two New Yorkers around the age of thirty, Tommy Albright and his friend Jeff Douglas. Jeff, who drinks too much, cannot comprehend his friend's dissatisfaction with a life that includes a find job and an attractive fiancee. Yet Tommy is deeply troubled and unwilling to settle down to the routine existence that is expected of him. Just then, the pair hear distant voices singing about a village called Brigadoon (Brigadoon), which is not listed on their map. Slowly, the village itself begins to appear in the mist.
On a road to Brigadoon, a group of Scottish peasants carrying baskets, jugs of ale, and other produce proceed to the town square (Vendor's Calls). The curtains part to reveal MacConnachy Square, the center of Brigadoon, a typical eighteenth century Scottish village. Once a week, the townsfolk engage in the tradition of setting up booths and carts to sell their wares (Down on MacConnachy Square)
We meet Angus MacGuffie and his flirtatious assistant, Meg Brockie, who sell milk and cream; Sandy Dean, who sells candy; and Archie Beaton, who offers wools, plaids, and other apparel. Archie's son, Harry, is a sensitive, scholarly youth, who is painfully in love with Jean MacLaren, the younger daughter of Andrew MacLaren, one of the town's leading figures. Jean is a shy girl, who that evening is going to wed Harry's rival, Charlie Dalrymple. Andrew has arrived to put up in full view a parchment written by a Mr. Lundie. It is a reminder of the second day of the village's blessing, a curious phrase that goes unexplained to the audience, but which is certainly understood by the townsfolk. Meanwhile, Jean's older sister, Fiona, tells Meg that she is in no hurry to get married and will do so only when the right man appears (Waitin' for My Dearie)
Tommy and Jeff arrive at MacConnachy Square and are regarded by the villagers with a degree of awe and curiosity that far exceeds a normal reaction toward strangers in a small town. When Tommy inquires about the references in conversation to a miracle, his questions are lightly evaded. The visitors are, however, invited to join the wedding festivities; and Charlie vows that his "rovin" days are over (I'll go home with Bonnie Jean"; "Dance)
Tommy reveals to gentle Fiona that although he is planning to marry his long-time girl friend in new York, he is doing so out of obligation to her, not because he is love. He is, however, attracted to the sweetness of Fiona and agrees to accompany her to a nearby hill to collect heather for the wedding (The Heather on the Hill). The duet draws them together, and they stare at each other, when thunder is heard in the distance. As the villagers race about to close their booths and carts, Fiona dreamily picks up her basket for the heather and strolls off with Tommy on her arm.
Meg has invited the weary Jeff back to her open shed, where he hopes to get some sleep. She, however, has other ideas and regales him with the details of some of her romantic escapades (The Love of My Life). When she concludes her spirited narrative, she looks down to discover that he has fallen fast asleep. She takes off her shoes, sits on a rocking chair, and begins to rock with a smile on her face.
At the MacLaren house, Jean's girl friends are helping her pack to move to her new home (Jeannie's Packin' Up). harry Beaton arrives to deliver Mr. MacLaren's new waistcoat and expresses his bitterness that he has lost Jean to Charlie and furthermore can never leave Brigadoon to advance his education and improve himself. After he leaves, the expectant groom appears to sign the family Bible. he calls to his bride, who chides him that it is bad luck for him to see her before the ceremony (Come to Me, Bend to Me", "Dance).
When Tommy and Fiona arrive, it is apparent that they have fallen in love. Jeff also turns up, obviously having had a romantic romp with Meg. Tommy tells his friend he has never felt better in his life (Almost Like Being in Love).
When Tommy's eyes fall on the open Bible, he shows Jeff that there is an entry for the wedding of one Andrew MacLaren, July 2, 1719, and the births of children Fiona, October 10th, 1722, and jean, April 8th, 1728. The ages correspond perfectly with the MacLaren family they both know today. The latest entry reads, "Married: Jean MacLaren to Charles MacPherson Dalrymple, May 24th, 1746." When Tommy asks Fiona the meaning of the mysterious entries, she says that the town's schoolmaster, Mr. Lundie, the dominie, must provide the explanation. Confused, Tommy and Jeff exit with Fiona.
Outside his house, the kindly and benign Mr. Lundie tells that although any resident of Brigadoon is able to explain the miracle to a visitor, it would not be believed. Therefore, the task has fallen to him. Two hundred years ago, the Highlands of Scotland were plagued with witches, who were taking the folk away from God's teachings and putting the devil into their souls. Mr. Forsythe, Brigadoon's aged minister, fearing for his flock's fate after his death, decided to ask God for a miracle. Early on a Wednesday morning, he went out to a hill beyond Brigadoon and asked God to make the village and its people vanish into the Highland mist, to reappear in the world for one day every hundred year, not long enough to be touched by the outside world. That was Wednesday: today is Friday, two days later to the villagers, yet two centuries to the rest of the world. The sacrifice for the miracle was Mr. Forsythe's life, for when God made the town vanish, Mr. Forsythe could not return. If any resident of Brigadoon should leave its borders, the enchantment is broken. The town will vanish forever, although a stranger may come to live there if that person truly loves and individual in Brigadoon. After Fiona leaves to dress for the wedding, Tommy is assured by Mr. Lundie that everyone is happy in the village.
The site of the wedding is the kirkyard outside what seems to be the ruins of the Gothic village kirk. With great solemnity, the clans begin to arrive, their family names called out as they appear, one by one (Entrance of the Clans)
Mr. Lundie explains to the gathered crowd that although there is now no minister in Brigadoon, it is proper according to Scottish law that two people who vow to love each other for a lifetime can be legally wed. Charlie and Jean exchange vows and are declared husband and wife by Mr. Lundie. There is a joyous wedding dance, interrupted by the appearance of Harry Beaton, who enters holding two swords aloft. He places them on the ground and leads the group into a wildly frenzied "Sword Dance". He then approaches Jean and asks her to dance with him, which she does, faster and faster. The crowds part to reveal Jean sobbing on the ground, harry standing over her. She rises and runs to Charlie. In pain and anguish, Harry cries out that he has wanted Jean too much and is leaving Brigadoon. "'Tis the end of all of us! The miracle's over!" He runs off, all the men, including Tommy and Jeff, in desperate pursuit.
The sun has fallen, and a mist beclouds the dark forest near the borders of Brigadoon. The frantic Harry Beaton runs in, looks around, and flees, closely pursued by the men, who know that if Harry crosses the village border, the town will vanish forever. Tommy enters with Jeff and tells him to hold harry fast, for many lives depend on their actions. The pursuit continues, when suddenly we hear a painful cry in the distance. Angus, Tommy, and the others enter carrying the dead body of Harry, who apparently fell and crushed his head. Despite the threat the young man posed, the men of the village express regret over his death and exclaim that they wanted only to prevent him from leaving (The Chase).
On the way to the forest a few minutes later, MacLaren reassures Fiona and the women that harry was stopped. not even Archie Beaton is told that his son has died, for fear of ruining the wedding festivities. Fiona is relieved to learn that Tommy has not left and professes her love for him. He too tells her that after one short day, he feels he cannot live without her for fear of joining the other lonely men he sees in life (There, but for You, Go I).
Following a jolly country dance by the townsfold, Meg appears to the delight of all and recounts the roistering goings-on at her own mother's wedding day, which she recalls vividly, because she was there (My Mother's Weddin' Day).
The dance is suddenly interrupted by the somber droning of bagpipes. Everyone steps back in horror, as Archie Beaton enters, carrying the body of his son. Maggie Anderson, a young villager, who loved Harry but was spurned by him, dances the piobrochead, a traditional funeral dance of mourning, accompanied by solemn pipes and drums.
When Tommy informs Jeff that he plans to give up everything and remain in Brigadoon, his friend convinces him that he has been hypnotized by Highland voodoo, that after a few weeks back home, he won't feel a thing. Jeff adds that he accidentally caused Harry's death by sticking out his foot and tripping the young man as he ran by.
Reluctantly, Tommy tells Fiona that he does not trust his own feelings and must leave, yet they affirm their mutual love (From This Day On). The day is ending. Fiona moves away from him and vanishes into the darkening mist, her voice growing faint, as she vows her love. Brigadoon is gone. Tommy slowly exits.
It is four months later. In a New York bar, Frank, the bartender, continues to ply Jeff with bourbon. tommy enters and tells them that after quitting his job a month ago, he went up to a farm in new Hampshire. He is not even sure that he wants to get married.
Just then, Tommy's fiancee, Jane Ashton, enters. She is chic and a bit severe in style. As she chatters on and on about her plans for their wedding and the location of the house they will own, images of Brigadoon appear on the other side of the stage, as Fiona, Charlie, and the others sing fragmentary reprises of their songs. Torn between his two worlds, Tommy startles Jane by calling off the wedding. He phones Jeff and tells him to get plane reservations for the two of them. Even if the town is not there, he wants to see where it was.
It is three nights later, in the same forest where the two Americans first saw Brigadoon. Tommy cannot believe that the village was just a dream and cries out, "God! Why do people have to lose things to find out what they really mean?" As they turn to leave, the chorus begins to sing in the distance. Suddenly, a sleepy Mr. Lundie appears in the mist and remarks that Tommy must truly love Fiona, for the old man was awakened in the middle of the night. He adds that when you love someone deeply, anything is possible, even miracles. Tommy moves toward Mr. Lundie, looks back at the bewildered Jeff, and exits with the wise schoolmaster.