An obscure French horror film on a Metro platform? Far from it.

The provenance of a photo, which had long stumped the Library of Congress for years, has been solved.

The photo shows two actors, one dressed as an alien and a woman with a prop gun. Keen-eyed sleuths confirmed a while back that they were on a BART platform. But what has remained unclear is which BART station - and what film was being promoted.

In a blog post in 2016, the Library of Congress pleaded for tips about the photo.

Earlier this month on Twitter, film historian Scott Jordan Harris called on movie lovers, horror fans and sci-fi aficionados to help the Library of Congress ID the film.

A staff librarian "familiar with both French cinema and the Parisian transportation system believes this might be a French film," the post read.


Mais non!

KTVU confirmed Friday that the picture in question was taken in 1974 at the 24th Street Mission BART Station in San Francisco's Mission District.

But it wasn't for a film. It was a promotional photo taken for "The Great Air Robbery," a play put on by the San Francisco Mime Troupe that premiered in August 1974.

After KTVU aired the picture, it caught the attention of the stage manager from the San Francisco Mime Troupe.

"She said, 'There's a picture on KTVU, and I think it's from a mime-troupe show," said resident playwright Michael Sullivan.

"Yeah, mystery solved, which is great," Sullivan said. "And it's also cool to have the Library of Congress go 'oh my goodness, this ground-breaking photographer of this amazing cinematographer. What film is this from!??' It's like, 'yeaaah... it's a Mime-Troupe show."

Unlike its name, the mime troupe is far from silent. It's well known for its political satire and free shows in San Francisco parks.

" 'The Great Air Robbery' was kind of a dystopic film noir, where pollution had gotten so bad that people were struggling to breathe. So corporations had figured a way to commoditize fresh air," Sullivan said.

Act III of the play was set in the BART tunnel, according to a playbill on the troupe's website.

KTVU revealed the story behind the photo to BART spokeswoman Alicia Trost. The transit agency had scoured its film-permit archives, to no avail.

"This is really exciting!" Trost said. "You cracked the code. We've been searching for a couple of weeks. Not only that, someone actually sent me this picture a couple of years ago, and I did a little bit of research, and I really didn't come up with anything."

She added, "I love that this is something very San Francisco, that they went into our Mission Street station. They got this amazing photo and that decades later people were still wondering what's behind it. And you figured it out."

The San Francisco Mime Troupe performs in the city's parks every weekend from the Fourth of July weekend to Labor Day. The group is celebrating its 60th anniversary next year.