Disclosure: Mission Local produces a radio program every other week through BFF.fm, a community radio station located in the Secret Alley.

The Secret Alley does a good job of living up to its name. From the street, you would never guess what goes on inside the second-floor creative workspace. But in a nutshell, here’s what happens behind the nondescript entryway: Stuff gets built. Wild stuff.

While the Alley, at 180 Capp St., is essentially a group of creative workspaces enveloped in a giant set piece, its original builders have expanded the reach of their imaginations to the downstairs gallery, the Galallery. And fall is the season of the Galallery’s most ostentatious exhibition: Halloween.

“A lot of people really extend themselves to the arts during Halloween,” says Noel Von Joo, one of the founders of the Secret Alley.

He and three others developed the Secret Alley in 2005. It’s a fantasy world, where a ship hull emerges from the treetops and a diner dissolves into a cinema marquee — all hidden behind a door marked “janitor’s closet.”

The group of film and other artistic freelancers needed a space to work after having to leave a spot on Valencia Street they had unwittingly rented, then renovated, from a person who turned out have been only posing as the landlord.

Still brimming with creativity, the group developed the Alley at their new space. Over the years, some of the original group moved on or away, and new ventures came in. Among the latter was a community radio station, BFF.fm (which stands for “Best Frequencies Forever”).

BFF founder Amanda Guest originally rented a spot in the Alley as a personal workspace, but had long toyed with the idea of revisiting her college radio days with a Bay Area-focused station.

“I casually mentioned my dream to start a community radio station,” Guest says, which immediately elicited an offer from Von Joo to put it in the Alley. “That was the only excuse I needed to start it.”

BFF grew rapidly, and has since been voted onto local “Best Of” lists — among them SF Weekly’s — and attracted the attention of local writers

The downstairs gallery space, in the building’s long entry hall, was at first sporadically curated. With filmmakers, screenprinters, DJs and other artistic types percolating through, the gallery inevitably became an extension of the Secret Alley, and was dubbed the Galallery for reasons nobody can really explain.

Media collided in synergistic ways — like when some DJs started a BFF show playing sound collages during the full moon, and a visual collage artist began adding her interpretations.

Eventually, two women involved with the Alley stepped forward to make the gallery a nonprofit and begin curating in earnest. Things were getting serious — but never too serious. Everything at the Secret Alley and the Galallery has a playful streak, and the Halloween installations only got increasingly elaborate.

“There’s this feeling of possibility and fantasy where you can transform yourself and become another character,” Guest says. With the Halloween exhibition, that expands to an entire space: “It’s kind of like putting a costume on the gallery.”

This year, to launch yet another spectacle of allegedly even more epic proportions, the group has begun fundraising. The productions are made possible, after all, through both collaborative volunteer work and deepening holes in Von Joo’s wallet.

“I feel like we’re stepping up our game,” he says. “Everyone works together to do it, it’s a big collaborative art project.”

True to their name, the Secret Alley’s creators are tight-lipped about this year’s theme. But recent years have seen the Gallalery turned into the site of a crashed UFO, complete with an animated scene of an alien being chased by a foe through the wreckage, projected within the vessel. Another year, the Gallalery became a haunted pumpkin patch, home to a massive animatronic pumpkin monster.

Or how about the time they set up a “death ray,” which visitors could aim from their seat in a barbershop chair outfitted with several enormous subwoofers that would quake with sound as the user deployed the ray on some unlucky fictional world? One particularly enthusiastic user is rumored to have been Tom Waits, who had been taking acting classes upstairs.

In the past, the denizens of the Secret Alley have simply flung open the Gallalery doors and beckoned in the curious, but with the ever-more-intricate projects that have sprung up, Halloween has become a ticketed event, allowing visitors to spend 15 or 20 minutes exploring every lovingly constructed cranny.