In 1917, Paul Mescal plays Lionel Worthing, a music student at the Boston Conservatory, who meets fellow student Josh O'Connor David White at a pub, and the two instantly bond over their shared love of folk music before returning to David's apartment for an intimate night. As their connection deepens, the war darkens the horizon: America enters World War I, David is drafted, while Lionel, who is ineligible due to his eyesight, returns to his home state of Kentucky when the conservatory closes. He puts music aside to tend the family farm after his father dies suddenly, a loss that weighs on him and those around him, including Lionel Sr. (portrayed by Raphael Sbarge).
In 1919, Lionel receives a letter from David announcing his return from Europe, his employment at a Maine college, and a department-funded trip across the state to collect folk songs on wax cylinders, inviting Lionel to accompany and assist him. The two reunite and travel around, capturing songs from people of varying walks of life and renewing their relationship. They eventually part again as David must return to work and Lionel plans to travel to Europe. Lionel continues to write letters, but the correspondence ends after a year when he never hears back.
In 1923, Lionel, now living in Rome, tells his lover Luca of his dissatisfaction singing in a local choir and of taking a job at the University of Oxford, ending their relationship on bad terms. A year later, Lionel serves as conductor for the school's choir and becomes involved with student socialite Clarissa Roux, who invites him to meet her family at a country manor. During the trip, Lionel is overwhelmed with memories of David, and the relationship with Clarissa ends when Lionel must suddenly return to the United States to comfort his dying mother, Molly Price.
After tying up his family affairs, Lionel travels to Maine to find David, only to learn from a colleague that David had died some time after their trip and that his department never actually commissioned the wax cylinders trip, leaving the location of the cylinders unknown. The colleague directs Lionel to David's widow, Belle, Hadley Robinson. Belle reveals she recognizes Lionel, explains how she and David became involved, and shares that David's death was a suicide linked to shell shock from the war. She returns his letters and promises to send the cylinders if they can be found. Lionel mourns David by revisiting his favorite places and recounting the songs that connected them, especially The Unquiet Grave.
In 1980, Lionel, now an ethnomusicologist, is promoting his latest book when a package arrives containing the wax cylinders, including one recorded on the day of David's death. On the recording, David apologizes to Lionel and thanks him for their time together before singing Silver Dagger, the song Lionel sang to David when they first met.
