Dying in the arms of a fellow prisoner of war, Lt. Nathaniel Minter Dial pleaded for one thing: that his Naval Academy ring be given to his wife.

The commander of the USS Napa during World War II had survived for 21/2 years at the notorious Cabanatuan prison camp in the Philippines, hiding the gold ring with the eagle insignia by tying it inside his tattered clothing. A friend, Lt. Douglas Fisher, promised he would hand-deliver the keepsake.

But it would take 17 years, an improbable find at an excavation site, and a last-minute rescue from a Korean pawnshop before the ring would find its way to Dial's son in Philadelphia - only to be pilfered by burglars, prompting yet another search.

The journey is chronicled in The Last Ring Home, a documentary to be shown at a special screening Tuesday at the Bryn Mawr Film Institute and televised Friday on WHYY. The film is produced by Dial's grandson and namesake, Minter Dial, a London resident who spent much of his early life at Ardrossan, the Main Line estate of socialite Hope Montgomery Scott, his great-aunt and inspiration for Katharine Hepburn's Tracy Lord of the film The Philadelphia Story.

Growing up, Dial, founder of a digital-consulting concern, knew little about his grandfather, the man wearing his Navy dress whites in a cherished family photograph. In the picture, Lt. Dial is holding his 3-year-old son, Victor - Minter Dial's dad - on his lap.

"My father never talked about his father," said Minter Dial, 52.

Lt. Dial's story was in a black box full of love letters and Navy documents that an aunt had packed away.

In 1991, Minter Dial was working in Washington when he got a call that changed everything. The woman on the line was looking for Minter Dial. She wanted to invite him to the 65th reunion of his high school graduating class.

"I was 26," Minter Dial said. "I told her, 'You must have the wrong Minter Dial.' "

The woman was looking for the grandfather who had attended the former Western High School in Washington. She told the younger Dial that she had located nine other graduates, and recognizing an opportunity to learn more about the man in that family photograph, he wrote letters to the classmates.

With that, Minter Dial, who also would write a biography of his grandfather, launched his 25-year research project.

He scoured documents at the National Archives, interviewed classmates; read history books and memoirs; traveled to POW conventions, the Philippines, and South Korea; and opened his aunt's black box.

He pieced together the story of the dashing son of a senator from South Carolina who had commanded a ship in Manila Bay during World War II.

In the spring of 1942, after the surrender of Allied forces in the Philippines, he and more than 75,000 other troops were taken prisoner. Lt. Dial was held at Cabanatuan, where prisoners constantly battled malaria, slept in thatched huts, and fought off starvation from a diet of rice almost exclusively.

Lt. Dial died in January 1945 after he was herded onto a POW ship that was hit by friendly fire. Lt. Fisher took the ring, but he lost it when he was transported to a prison camp in Korea. After the war, Fisher visited Lt. Dial's widow and the couple's son and daughter then living in California. Fisher apologized for losing the ring.

"He gave me his watch," said Victor Dial, 78, who was 7 at the time of the visit. "That's when we found out the circumstances of [my father's] death. I had trouble dealing with the suffering he went through."

In 1962, Victor Dial was a young Ford Motor Co. trainee in Philadelphia and courting Alix Montgomery, of Villanova, when the improbable happened. An excavation by the Navy was underway in Inchon, South Korea, and a worker at the site discovered a ring buried in the dirt. He tucked it away and told a colleague at the site he planned to sell it.

It so happened that the colleague, who also worked as a driver for Navy officers, spied a similar ring on the finger of one his passengers, Rear Adm. George W. Pressey. When the driver informed the admiral about the ring, the two men quickly searched Inchon pawnshops.

Pressey and the driver struck gold, arriving just as one store owner was about to melt it down. Pressey purchased the ring, and inside saw the inscription, "Dial," the name of a close friend and Annapolis classmate. Pressey wrote a letter to Victor Dial and mailed the ring.

"It was overwhelming," said Victor Dial, who drove the box containing the ring to New York, so that his mother would be the first to see it. "We all had a good old cry," Victor Dial said.

After his mother's death in 1963, Victor Dial, then living in Paris, placed the ring on the wall in a frame that also held his dad's Navy Cross and Purple Heart. But five years later, the unimaginable happened. Burglars broke in and stole the framed ring and medals.

"I was totally crushed," Victor Dial said. For weeks, he scanned the tables at a popular Paris flea market, hoping he would find the ring.

The ring is still missing, but what Lt. Dial's family members have gained is a detailed account of the life of a Navy lieutenant who would read books aloud to his fellow prisoners to keep up their spirits.

And Minter Dial's project has provided a pathway for Victor Dial to remember and talk about his father.

"All of a sudden he started to deal with [the trauma], and his whole demeanor has changed," said Elisabeth Carr, Victor Dial's daughter and a physician in Baltimore.

Minter Dial is hoping that the documentary, which is also being shown at film festivals, will yield more miraculous fruits. "It is my hope that we may get people looking for the ring," Minter Dial said.

Finding it 50 years later, he acknowledges, is "introducing some fantasy," but given what has happened so far, he's not ready to rule out the fantastic.