Sep 30, 2014 10:58 AM

The towering bluffs, panoramic beaches and roadside seafood joints of Montauk have been the longtime home to generational Bonackers, as well as the newly sought-after destination of the rich and famous from around the world.

But its beauty, rivaled by few others, is far from common ground between the two groups, which are separated by a strong sense of identity centering on residency labels—“locals” and “weekenders.”

This clash—no matter which side of the hedges, or Shinnecock Canal, one resides—is undeniable, and it is a story waiting to be told through the sinful yet passionate tale of Alison and Noah, the lusty protagonists of Showtime’s newest drama, “The Affair,” which premieres on Sunday, October 12, at 10 p.m.

Shot primarily in Montauk, the show follows the journey of Alison, a local waitress portrayed by British-born actress Ruth Wilson, who meets Noah, a wealthy Manhattan schoolteacher (Dominic West). While both are, for the most part, in love with their spouses, the two find themselves quickly wrapped up in an intense romance, told in flashbacks as they recount the details of their affair to help a detective solve a case, according to Sarah Treem, one of the show’s creators.

“The interesting thing is, the way they remember Montauk is completely different,” Ms. Treem, who is also a co-executive producer for Netflix’s “House of Cards,” said during a telephone interview on Monday evening from her home base in California. “For Alison, it’s normal—it’s her home. For Noah, it’s this summer town, and it’s a little bit wild, and there’s no rules. He’s kind of escaping his own reality. They’re both engaging with the place in a different way”

The juxtaposition between the two characters, Ms. Treem explained, extends far beyond how both characters tell their sides of the story, which is only the “top layer” to the plot, she said.

Alison hails from a family of ranchers and is married to her longtime love, fellow Montauk native and dude-rancher Cole, portrayed by Joshua Jackson. On the other hand, Noah has gained most of his wealth through his wife, Helen (Maura Tierney), an eco-friendly store owner whose family owns an estate in the hamlet.

“Alison’s family is supposed to own Deep Hollow Ranch, and that land has been in their family for generations,” Ms. Treem said. “They’re sitting on a fortune, but they don’t ever want to leave it. Wherein, with Noah, he married into this very wealthy family, but he himself has no money. He just lives like a wealthy person.”

Montauk provided the perfect backdrop for the story, because the town itself acts as more than just a location, said Ms. Treem, who spent her childhood summers with her grandparents in Amagansett.

“I just insisted that you couldn’t capture the spirit of this town unless we shot the show there,” she said of filming. “You couldn’t create Montauk anyplace else, even if you wanted to. We didn’t want a substitute. So I think people will get that when they see the show. It’s pretty strong.”

In order to fully grasp and portray the cultural and socioeconomic rift between locals and visitors, Ms. Treem turned to her grandparents, childhood friends and family acquaintances for a deeper understanding. “I had a lot of conversations with just about everyone I knew,” she said. “It’s fascinating, having a new group of people coming in, a new class of city people moving out there, making it their permanent residence and creating a new community that’s a hybrid of locals and city people who are united in this idea that they all really love this place and want to preserve it.”

The pilot episode of “The Affair” was filmed in Montauk over the course of a few days two summers ago, she said, and the crew returned this past May to continue filming, on and off, for about five weeks total, wrapping up its final shoot in early September.

While she would have liked to film the entire series on location, Ms. Treem said permitting wasn’t granted, given the East End’s busy summer season. The rest of the scenes were filmed on other parts of Long Island, closer to Manhattan.

The filmmakers “were a bunch of true professionals on every level,” said Andrea Terry, co-owner of The Lobster Roll, where Alison is portrayed as a waitress and, subsequently, many scenes were shot. “It’s very stressful to have someone come in and disassemble [your space] and create scenes. They must have had 150 staff members on premise, and they left the next day. Sometimes we were open the next day for business ... You’d walk in the next day and never know anyone was here.”

Ms. Terry said she was approached by one of the show’s directors during business hours, requesting to use the space. “I think they were driving out to Montauk, saw the restaurant and stopped to come in,” she said. “They asked me if I’d be interested in having them film there, and the rest was history. I was kind of nervous at first, but I really have nothing but great things to say about the experience.”

The show also took up temporary residence at the Depot Art Gallery at the Montauk train station for a few scenes, said Anne Weissman, the space’s treasurer. “They chose some dates when we were closed to the public, came in and did their thing,” she said. “They were fantastic to work with. At one point, a few weeks ago, they were even making snow in the parking lot. Needless to say, it was gone by the time I got in the next morning.”

Ms. Treem said the 10-episode show started off “low budget,” but quickly transformed into a mid-budget show—although not on par with “House of Cards.” Unsure whether “The Affair” will be signed for a second season, she remains hopeful.

“I consider the show a love letter to Montauk,” she said. “So I hope people take that away.”

“The Affair” will premiere on Sunday, October 12, at 10 p.m. on Showtime. For more information, visit sho.com/sho/the-affair/home.