GROTON -- Just minutes before Clover Farm Market reopened on April 26, following a months-long renovation, David Melpignano saw a boy standing outside the door.

Four months had passed since 14-year-old Moss Monaghan cleaned the floor and windows to help retiring storeowner Winthrop "Winnie" Sherwin shut it down and pass it on to someone else, and the boy couldn't wait to see how the store had transformed.

It turned out what's magical about the historic market was still there, Moss says.

Even though Sherwin was no longer behind the counter, asking kids if they could tell him how much they owed for candy without him calculating for them, Moss sill felt home, and he kept coming back to the store every day for two straight weeks.

Melpignano asked Moss what makes the store so special. The teen said he didn't know. But the smile on his face as he talked about the store might explain it all.

"It's the atmosphere," Moss said. "It's just nice to come here and hang out."

Over the past 10 months, Melpignano has been recording such words and facial expressions of the faithful customers of Clover Farm Market through a video recorder lens. The film producer, who once taught cinematology at Boston College, came to know Sherwin when Melpignano moved two blocks from the store in West Groton three years ago. Late last year, his girlfriend, Jan Hurst, bought the store from 88-year-old Sherwin, and Melpignano helped her renovate it as a cozy country store featuring gourmet sandwiches and organic and heirloom vegetables.

Watching townspeople gather at the store to bid farewell to Sherwin -- and sensing enormous support from them for the store reopening -- Melpignano started to wonder what Clover Farm meant to them. So he picked up his camcorder and began asking people just that.

The result is a short documentary, called The Keeper. The 20-to-25-minute film will premiere Saturday, Sept. 8, when Hurst hosts the Down-Upon-A-Squannee River Festival in West Groton Square across from the market. The screening will take place inside the store at 7:30 p.m., following the festival, which runs from noon to dusk.

Melpignano, a Milford native who owns a stock-footage business, has worked on films of all genres, from production of corporate marketing materials to editing of Thanatos Rx: The Death Penalty Debate in America, produced by Boston filmmaker Maryanne Galvin.

But his latest documentary is a special project to him because of Sherwin.

Sherwin began working at the store 70 years ago, when it was called Red & White Food Store. He operated the business with his late brother, Lonnie, for a half-century.

"He made you feel part of his life simply by him asking about you," Melpignano said of Sherwin. "There was an immediate bond because he is interested in you."

Many residents share Melpignano's sentiment. Some call the store the "heart and soul" of West Groton.

"Somehow, I wanted to package the whole feeling around the store and give it back (to the community)," Melpignano said.

The Down-Upon-A-Squannee River Festival will feature live music and food. For more information about the festival and film screening, contact Clover Farm Market at (978) 448-0010.