A sad note runs like a minor seventh through this otherwise foot-stompingly joyous movie about a handful of the great backing vocalists in rock and pop music.
It's a ringing, resounding tribute to a handful of (predominantly African American) women who have become what might be called household voices, all the while remaining unknown names.
You know them: Merry Clayton sang up a storm in 1969 ("... it's just a shot away ...") on the Stones' Gimme Shelter; Darlene Love sang the 1962 hit He's A Rebel, and producer Phil Spector got the The Crystals to lip-synch; Lisa Fischer, who has backed The Stones on every tour since 1989, does that lovely coloratura on Sting's songs; Judith Hill was rehearsing with Michael Jackson when he died, and sang Heal the World at his memorial service.
The elders of this quartet kickstarted the habit of white bands having black backup singers (hilariously, they call their vanilla predecessors "readers", as opposed to "singers"; "They couldn't do anything without the [sheet] music in their face," says one) and their history is rich in thrilling musical moments.
But as it progresses, its title takes on an elegiac tone: that 20 feet doesn't seem like much, but it's a gap that proves unbridgeable.
The film charts the painful and thwarted attempts of these women to succeed in their own right. There are tears in Clayton's eyes as she says, "I felt that if I just gave my heart to what I was doing I would automatically be a star."
Those born on the edge of the spotlight should not presume to step into it, we are being told; the socio-political implications are scarcely obscure. Says Bruce Springsteen, one of a dozen big stars who provide mostly banal perspectives: "The walk to the front [of the stage] is complicated."
These sobering subtexts notwithstanding, make no mistake: 20 Feet From Stardom is a paean to the soul diva and a testament to the energising power of music. It's no accident that almost all these women had pastor fathers and cut their singing teeth in church.
If there's sadness about dreams that never happened, there's a fierce pride, too. These women have no problem at all with the line in Lou Reed's Walk on the Wild Side "And the colored girls go/ Doo do doo ...", because that's what they do.
But if you think that's all they do, you're in for a big surprise. Anyone who gets Springsteen singing backup to her, as Darlene Love does in the finale, has got to have something going for her. Recommended.
Cast: Darlene Love, Merry Clayton, Lisa Fischer, Judith Hill, Tata Vega, Jo Lawry
Director: Morgan Neville
Running time: 91 mins
Rating: M (offensive language)
Verdict: Sweet, sad, thrilling, energising, unmissable.