In 1979, Carly Simon opened the Hot Tin Roof nightclub with two partners in a steel hangar off a dirt road near the Martha’s Vineyard Airport. To decorate the venue, she hired Margot Datz, a 26-year-old sculptor who had recently moved to the Vineyard from New Orleans and who happened to have spent many adolescent hours studying the way the light diffused through Ms. Simon’s skirt on the cover of her 1971 album Anticipation.

Longtime friends and artistic collaborators.

Jeanna Shepard

Longtime friends and artistic collaborators.

Jeanna Shepard

Eager to secure the job and as much a fan as ever, Ms. Datz said she would do the whole place for $2,000 including materials: a proposal that essentially required her to work for free. The club was built and finished in 67 days, according to the Vineyard Gazette archives.

The job would lead to decades of artistic collaboration between the two women, including dozens of murals in Ms. Simon’s homes and four illustrated children’s books. But for Ms. Datz the encounters with her idol were initially overwhelming. When they first met, Ms. Simon was 34 years old, a creative powerhouse with a string of top-10 hits, and a mother.

“I was this small-town girl, and it was like meeting God or something,” Ms. Datz said as she reminisced with Ms. Simon in Ms. Simon’s Vineyard Haven home. After it opened, the Hot Tin Roof routinely drew lines of hopeful patrons that stretched out to the road. Ms. Datz painted hubcaps commemorating some of the notable performances: Bonnie Raitt, Peter Tosh, Cyndi Lauper, James Taylor, the Blues Brothers and Ms. Simon. Ms. Simon’s phone rang all day, she said, with calls from people hoping she could get them in.

“You knew that if you went there you’d be a part of some fun activity, you know, something that would be talked about later,” Ms. Simon said.

When she was planning to create a music video for her 1983 song You Know What To Do, shot on the Vineyard, Ms. Simon again called Ms. Datz for help. In the video, Ms. Simon scampers down the stairs of her house and into the woods to meet a somewhat sinister lover.

“There’s the dress!” Ms. Simon said as the two women watched the video together during an interview, Ms. Datz for the first time. The dress is blue and translucent. It was handmade by Ms. Datz. “I remember doing the measurements in front of this mirror,” Ms. Simon said.

The friendship began when Ms. Datz did the murals at Hot Tin Roof, the storied Island nightclub co-owned by Ms. Simon.

Jeanna Shepard

The friendship began when Ms. Datz did the murals at Hot Tin Roof, the storied Island nightclub co-owned by Ms. Simon.

Jeanna Shepard

“I had collected antique lace,” Ms. Datz said. “It was a hobby, and I had these beautiful old lace collars that I sewed onto the dress.”

After that collaboration, several years passed, and the two women lost touch until Ms. Simon wrote a children’s book based on her daughter, Sally, about a bear who refuses to go to sleep. She asked Ms. Datz to illustrate it. The story was called Amy the Dancing Bear and the publisher gave Ms. Datz just five weeks to complete the illustrations.

“I set up an art table in the living room, and I put two little mattresses underneath it for my children, and they would kind of live under my art table and eat pizza under there while Mommy worked 15 hours a day to try to get this done,” Ms. Datz remembered.

In her illustrations, Amy the Dancing Bear wears a pink skirt and twirls a vine of purple flowers.

“It’s so much fun to see her come up with a character,” Ms. Simon said.

Ms. Simon's home is decorated with Margo Datz murals.

Jeanna Shepard

Ms. Simon's home is decorated with Margo Datz murals.

Jeanna Shepard

Three children’s books followed in quick succession, including an adaptation of one of Ms. Simon’s lovesongs called The Fisherman’s Song. After that, they turned back to the Hot Tin Roof, which was being renovated and reopened. Ms. Datz filled it with new murals of fishermen and farmers, kissing in cornfields and dancing by the sea. She also began painting in Ms. Simon’s house, which is now full of her work: a swan paddles past lily pads, a painted hen sits in a laying box, painted flowers creep up around doorways, and vines cover indoor columns.

Sometimes, Ms. Datz painted while Ms. Simon worked out new music on her piano. Their conversations inspired many of Ms. Simon’s songs, including Happy Birthday.

“I remember writing that song,” Ms. Simon said. “It was both of our birthdays, and the first line of that song is, ‘It’s all of our birthdays this summer, another year older, another year younger.’”

Ms. Datz continues her work in the house, moving recently to the studio where Ms. Simon has written much of her music. Reflecting on their friendship, the singer and the painter fell into an easy rhythm. They remembered the perfumed waitresses who used to serve illicit drinks at the Ocean Club, how people had to lean in to be heard over the music in the shadowy corners of the Hot Tin Roof, how a comet once glowed in the nighttime sky over Sengekontacket for three whole months.

“I think part of the journey of greatest importance for me with you was learning to move from awe to intimacy,” Ms. Datz told Ms. Simon. “And over the years, I would notice that if I got nervous you would get nervous, and I thought, I’ve got to just stop getting nervous. I’ve got to be myself.”

Margot Datz will have her annual art show at the Grange Hall on Saturday, August 3, from 4 to 8 p.m.