Act One

Tommy Albright and Jeff Douglas from New York are hunting on vacation in the Sottish Highlands and get lost on their first night out. In the distance they hear eerie music from a nearby town ("Brigadoon"). They follow the music and discover a fair, with the townspeople in traditional Scottish garb ("McConnachy Square"). The MacLaren family, Andrew and his two daughters Jean and Fiona, arrive to purchase wedding supplies for Jean's wedding to Charlie Dalrymple. The thought of Jean marrying anyone other than him devastates Harry Beaton, who dismisses devotion from other ladies. Jean's older sister, Fiona, however, has no interest in rushing into marriage ("Waitin' For My Dearie"). 

Tommy and Jeff join the MacLaren's for a meal at their home, where the dairymaid Meg Brockie instantly takes a shine to Jeff. Jean's fiancé, Charlie, enthusiastically arrives, ecstatic at his upcoming nuptials ("Go Home with Bonnie Jean"). Though Tommy is engaged back home in New York, he shares a romantic morning with Fiona ("The Heather on the Hill"). Meg continues to pursue Jeff, who would rather nap ("The Love of My Life"). 

Jean and friends prepare for her new life ("Jeannie's Packin' Up"), while Charlie yearns for a glimpse of his love from outside ("Come to Me, Bend to Me"). Jeff arrives in traditional Highland trousers after his were damaged, and Tommy cannot contain his excitement of meeting Fiona ("Almost Like Being In Love"). Tommy discovers something odd in the MacLaren family bible — all the dates listed are 200 years old.

Fiona sends him to the school master, Mr. Lundie, who explains that the town of Brigadoon magically remains hidden except for one day every one hundred years, so as to keep the town unchanged from the outdoor world. The townsfolk are forbidden to ever leave, lest the entire town disappear forever. Tommy inquires if an outsider could remain in Brigadoon, and Mr. Lundie tells him through love, anything is possible. 

A grand processional begins the wedding. Charlie and Jean are married, and a traditional wedding dance follows featuring sword dancing led by Harry Beaton. The dance halts when Harry attempts to kiss Jean. Unable to be with the woman he loves, Harry  swears he will leave Brigadoon, end the magic and Brigadoon will disappear forever. 

Act Two

A frantic search for Harry by the men of the town ensues ("The Chase"). A loud scream is heard and Harry is discovered dead after falling on a rock. The men decide not tell the rest of the town until the following morning. Tommy sees Fiona and the two declare their mutual love ("There But For You Go I"). Tommy decides to find Mr. Lundie, so he can stay in Brigadoon with Fiona. 

In the village, Meg entertains the townsfolk with a story of when her parents were married ("My Mother's Wedding Day"). The reveling is interrupted by Archie Beacon arrives with his son's body, Harry. Harries unrequited love, Maggie, performs a funeral dance for him as they carry Harry to his burial. 

Jeff denounces Tommy's plans to stay in Brigadoon, and also confesses to accidentally tripping Harry, thus killing him. Tommy tells Fiona he loves her, but cannot stay in Brigadoon ("From This Day On"). She expresses her love once more as she fades away into darkness. 

Four months later, Tommy still cannot stop thinking of Fiona and Brigadoon. He tells his beautiful fiancé, Jane Ashton, that he cannot marry her (reprises of “Come to Me, Bend to Me,” “Heather on the Hill,” “Bonnie Jean,” and "From This Day On"). 

Tommy and Jeff return to where the first discovered Brigadoon and are devastated to find nothing there. As they begin to leave, they hear a faint hint of music and Mr. Lundie appears. He invites Tommy to stay, reminding him how with love, anything is possible. Tommy waves goodbye to Jeff as he fades away to remain in Brigadoon.