Browsing a New Hampshire thrift shop for old frames to restore, a local woman, who has chosen to remain anonymous to the press, bought a white frame with an old painting inside for $4. She had no idea that the painting was actually a rare work by renowned American artist N.C. Wyeth.

"It's everybody's dream," says Maine conservator Lauren Lewis, who helped determine the painting was an original Wyeth.

Who was N.C. Wyeth?

Newell Convers Wyeth was one of the "preeminent illustrators in the early 20th century," says Lewis. Among his best known book illustrations are the vibrant, swashbuckling images he made for Robert Louis Stevenson's 1911 novel Treasure Island.

He's also the father of painter Andrew Wyeth and the grandfather of painter Jamie Wyeth.

Why was the painting created?

The painting is one of four illustrations Wyeth did for a 1939 edition of Helen Hunt Jackson's Ramona, a novel about a Scottish-Native American orphan living in Southern California after the Mexican-American War.

This is the second out of the four Wyeth illustrations for Ramona that has been found. The other — Ramona and Alessandro on the narrow trail — sold at auction for $665,000 at Sotheby's in 2014.

This painting, "just disappeared completely for 80 years," says Lewis. She would like to know where it has been and how it wound up at the thrift shop.

Lewis hopes as news of this rare find circulates, perhaps collectors who own the other ones or have information about this one's whereabouts will come forward.

What happened?

In 2017, a woman found the artwork in a stack of frames at Saver, a thrift shop in Manchester, NH. According to the auction house Bonhams Skinner, the painting was "quite heavy and dusty." She paid the shop $4 for it.

Then this past May, while cleaning, she came across the painting in her closet.

Thinking it might have value, she posted images of it on a Facebook page dedicated to Wyeth.

"It started off with, 'Is this real?'" laughs Lewis, who curated exhibits with the Wyeth family as part of her work at the Wyeth Study Center at the Farnsworth Museum in Maine.

What struck her about the photos on Facebook was the label on the image on the back of the painting.

"N.C. Wyeth painted commonly on a brand of panel called Renaissance Panel made by the Weber company," says Lewis. Another, smaller label on the back identified it as an N.C. Wyeth and from the book Ramona.

After consulting with Christine Podmaniczky, curator emerita of the Brandywine Museum of Art and an expert in N. C. Wyeth, Lewis determined the work was indeed an original Wyeth.

What happens next?

The auction house Bonhams Skinner estimates the painting will sell for between $150,000-250,000 when it goes up for auction on Sept. 19.

Lewis says the thrift store shopper and her husband are not wealthy. "They are not your typical art collectors," she says. If the sale achieves expectations, "this would be life-changing for them."

She hopes that whoever purchases the Ramona painting will make it available to the general public.

"There's nothing like seeing an original painting," she says. "I do hope that it remains in a collection that will be willing to lend it — or even give it to a museum."