Mabel Stark (Mina Murray) and Pet (Ava Estrella) from the upcoming “W. R. Athskellar Cavalcade of Curiosities” burlesque Halloween show. (Photo: Rich Jarvis)

Mabel Stark (Mina Murray) and Pet (Ava Estrella) from the upcoming “W. R. Athskellar Cavalcade of Curiosities” burlesque Halloween show. (Photo: Rich Jarvis)

The carnival is coming to town – and staying for a while.

The Boston Babydolls classic burlesque troupe has put on its annual “Wrathskellar” Halloween-themed shows locally before, in Central Square, East Cambridge and Somerville’s Davis Square, but this time it’s bringing an extravagant “W. R. Athskellar Cavalcade of Curiosities” to Union Square and staying put for a solid month – from Oct. 3 to Nov. 2.

Past shows have been set in an underground tavern, but a move to Somerville’s Uniun arts complex allows the troupe to shift to a new storyline combining striptease and carnival sideshow with an entire midway as a backdrop.

“I felt like we had taken the existing production about as far as we could go with it,” said author and show director Scratch. “In 2011 we built a pop-up theater in East Cambridge and brought our decrepit tavern to life. Last year, we upped the level of immersion by taking over the Davis Square Theatre for a month, which allowed us to have real bar service, but we also utilized unusual spaces to create places like Bücher the theatre manager’s office and The Diva’s dressing room. We also pushed our production values with an amazing set on a rotating turntable … After that, I felt like that story had been told.”

Still, he said, “We wanted to change things up this year while keeping it true to the shows that have attracted so many people” in the past. The troupe has produced Halloween-themed spectacles since 2007, and introducing the Wrathskellar name four years ago.

In the new, interactive storyline, the audience becomes the prize in a confrontation between good and evil, and there’s plenty else new: a sparking tap dance, aerial performance and seven-piece band combines with popcorn, a fortune-telling tent and games where guests can try their luck, including a Shooting Alley and a strength-testing High-Striker.

“Every year we do something a little different with the show, but this year is wildly different, and I’m really excited about the direction we’re taking,” said Miss Mina Murray, co-founder of the Babydolls and headmistress of The Boston Academy of Burlesque Education.

Big, big show

But the sideshow concept meant finding a large, nontraditional performance space – something Scratch has aimed for in his productions since working on the American Repertory Theater’s “Sleep No More” when it filled an old school building in Brookline in 2009-10. “That had a big impact on me,” Scratch said.

After exploring setting up an actual carnival tent in Boston, but deciding Boston weather in October is too unpredictable, the troupe found an indoors answer in Uniun. Some of the carnival aspects of the show have been added since the decision.

“Theatrical productions are subject to the same law of physics that gases are – they’ll expand to fill the space allowed,” Scratch said. “It was a mix of both things: We suited the show to the pace, and found a space that suited the show.”

The W. R. Athskellar Cavalcade of Curiosities stars The Boston Babydolls, Zach Eisenstat and Regie Gibson, with Ava Henry and Kirby Russell. Music direction is by Alissa Coates, technical direction is by Hunter Heinlein and the show is written and directed by Scratch.

The show is designed to be immersive and interactive, with organizers stressing that comfortable footwear is essential; the performance lasts for up to two and a half hours, and most of the audience is standing throughout.

The shows are 8 p.m. Oct. 3-Nov. 2 at The Uniun, 3 Sanborn Court, Union Square, Somerville. Tickets are $25 and $45 here or by calling (800) 838-3006.