Mockumentary captures the reunion of 1960s folk trio the Folksmen as they prepare for a show at The Town Hall to memorialize a recently deceased concert promoter.
When influential folk music producer Irving Steinbloom dies, his children organize a memorial concert featuring his three most famous acts: The Folksmen, The New Main Street Singers, and Mitch & Mickey.
The Folksmen trio consists of Mark Shubb (Harry Shearer), Alan Barrows (Christopher Guest), and Jerry Palter (Michael McKean). Their most famous folk song was "Old Joe's Place."
The New Main Street Singers are the second generation of the original Main Street Singers, formed by George Menschell (Paul Dooley), the sole survivor of the original group. Menschell sings and holds a guitar he cannot play. Performers include Terry Bohner (John Michael Higgins) and his wife Laurie Bohner (Jane Lynch). Laurie is a former adult film star and with her husband, is co-founder of Witches in Nature's Colors (WINC), a coven of modern-day witches that worships the power of color. Another member is Sissy Knox (Parker Posey), a former juvenile delinquent and daughter of one of the original Main Street Singers. They are managed by Mike LaFontaine (Fred Willard), whose fifteen minutes of fame came by way of a failed 1970s TV sitcom, Wha' Happened?, which lasted less than one season. The group, which is otherwise entirely white, includes one Filipino American member, Mike Maryama (played by Mark Nonisa).
Mitch Cohen (Eugene Levy) and Mickey Crabbe (Catherine O'Hara) are a romantic duo that released seven albums together until their traumatic break-up decades earlier. Their most famous song is "Kiss At the End of the Rainbow," during which the pair would actually kiss on stage.
After the three groups agree to the reunion performance, to be televised live on PBN, they begin rehearsals. The show itself goes off with only two hitches: two acts plan to play the same song, and Mitch temporarily disappears. In the finale, everyone joins together to sing "A Mighty Wind."
Six months after the reunion, Mickey is performing "The Sure-Flo Song" at her husband's trade show booth. Mitch is writing poetry again, claiming to be in a "prolific phase." Folksmen Mark Shubb is living life as a transgender woman, while still singing in his famous bass voice. LaFontaine is reviving an idea for a sitcom starring the New Main Street Singers. He wants to call it "Supreme Folk" and have each play Supreme Court judges by day, folk singers sharing a house by night.