One year ago this month, the Westhampton Beach Performing Arts Center tried its hand at hosting a concert headlined by a local act: the East End band Gene Casey and the Lone Sharks.

The PAC typically welcomes national headliners that play to large audiences across the country, while Gene Casey is more accustomed to playing in bars and dance halls. Nevertheless, it was an experiment that proved successful, and now Mr. Casey, his rockabilly band and an array of guest musicians will return to Westhampton Beach on Saturday, March 24, to do it again, with new additions to the lineup.

“It was a great vibe,” Mr. Casey said Friday of the first event. “It felt like a homecoming, and people are cheering for you. We don’t have any Grammys, we’re not doing a billion-dollar tour—but this is a validation and a celebration.

“Basically, you can’t get any more independent than we are. We do it ourselves. Good or bad, we are who we are.”

Mr. Casey, a former Sag Harbor resident who now lives in Southold, said that his first Westhampton Beach Performing Arts Center concert arose because of a smartphone app. “It was just really fortuitous circumstances,” he recalled.

He explained that the PAC’s executive director, Clare Bisceglia, would listen to his songs on Southampton’s public radio station, WPPB 88.3 FM. Not knowing who the artist was when the songs caught her ear, she used an app to identify the musician. Time and time again, the songs she liked and wanted to remember turned out to be Lone Sharks tunes.

“A local radio station beget a local theater reaching out to a local artist,” Mr. Casey said.

Playing at the 425-seat theater in Westhampton Beach is a breath of fresh air, he said. “To play in a theater with a great sound system, a nice big stage, great crew, even a dressing room—we didn’t even know what to do with the dressing room!—and a basket of fruit and cheese.”

It is a change of pace for the band, as well as the band’s followers.

“The only problem was, our fans love to dance,” Mr. Casey said. “And I just figure, well, for one night of the year, just sit back and let us do the driving.”

He will be joined again by his core Lone Sharks, drummer Chris Ripley and saxophone player Paul Scher.

Tricia Scotti—a singer who’s toured with Ronnie Spector, Wilson Pickett and Joey Ramone, and who appeared on stage with Mr. Casey for the first time last year in Westhampton Beach—also returns.

Mr. Casey said Ms. Scotti has been a semi-Lone Shark for the past year. “I always wanted to have a female vocalist, and I just never had an opportunity,” he shared. “She just moved out here. We met, and it really worked—a nice vocal blend.”

Just recently, they recorded an episode of “East End Underground” for LTV in East Hampton together.

Also returning are a couple of veteran Lone Sharks who are no longer members of the regular lineup.

“Our piano player throughout the ’90s, when we used to play the Wild Rose Cafe every week in Bridgehampton, was a guy named Andy Burton,” Mr. Casey said, noting that Mr. Burton also plays with Steven Van Zandt and Cyndi Lauper. “He’s a very much in-demand session and touring piano player.”

The other veteran is Mr. Casey’s brother, Vincent Casey. “He was the bass player in the early days of the Lone Sharks, when we were just playing the Corner Bar and Burke’s Roadhouse and so on. And he hasn’t really played with us in, like, 15 years. So he’s going to come up and do a couple tunes as well. He’s kind of representing the old Lone Sharks.”

In fact, the Lone Sharks have been playing music for 30 years on the East End. “So it’s kind of an anniversary,” Mr. Casey said.

It will also be a bittersweet occasion. The concert is being dedicated to the memory of Tony Palumbo, the longtime Lone Sharks upright bass player, who died of cancer this past October.

Mr. Palumbo was undergoing chemotherapy last March but still able to do the occasional gig, Mr. Casey said. He had been set to perform in the band’s Westhampton Beach show, but was forced to cancel at the last minute.

Mr. Casey said he reached out to all the bass players he knew, and at 3 o’clock in the morning Pete Crugnale texted him back, agreeing to fill in. “It was kind of a minor miracle that we were able to do the show.”

Mr. Crugnale, a founding member of the rockabilly band The Hornets and a bass player for several Long Island acts, will join the Lone Sharks this time as well.

A first-time guest at this concert will be Jeff Allegue, of another East End favorite, New Life Crisis. He is both a classical guitarist and a bass player who was a founding member of the Trans-Siberian Orchestra.

“We’ve been doing some writing and recording,” Mr. Casey said. “He’s going to come up and play a couple of numbers with us as a special guest.”

Mr. Casey expects to play 80 percent originals during the concert. “I write rock and roll tunes as well as ballads, so it’s not really that different than what we do in a bar,” he said. “But a little less classics, a little more originality.”

That includes some new songs Mr. Casey will be trying out. “Just to keep it fresh. For some reason, I can’t stop writing songs, even though no one really cares,” he said in a self-deprecating tone.

Mr. Casey’s songs “It Should Rain” and “It Turned Out That Way” were both featured on the FX series “Justified,” and his “Mañana, Mañana” was on another FX show, “Sons of Anarchy.” His songs have been included in films as well, such as “The Tall Man” starring Jessica Biel and “Being Charlie” by director Rob Reiner.

With a deep catalog of Americana- and roots-inspired music, Mr. Casey is taking care to ensure the set list is a good fit for the venue and occasion.

“It’s interesting,” he said. “When you’re playing a bar, it’s basically a four-hour night—three one-hour sets, and a certain type of pacing. So, this is different. This is kind of like a good hour and a half to two hours of music that you have to figure out how to pace it. And that’s a challenge. So we’re kind of working on that. Last year, it was just adrenaline that got us through.”

Mr. Casey admitted he thought last year’s concert was going to be a one-off. But the Westhampton Beach Performing Arts Center invited him to open for Dwight Yoakam in August and booked him for this second show as a headliner.

“It’s not a huge theater, but it’s a huge occasion for us, especially.

“And we get to put on our best clothes,” he laughed.

Gene Casey & the Lone Sharks will perform Saturday, March 24, at 8 p.m. at the Westhampton Beach Performing Arts Center. Tickets are $33. Call 631-288-1500 or visit whbpac.org