Andrew Frank and Hayley Plack talk about their engagement and the day when Hayley lost her engagement ring at Hayley's apartment in Washington. (Astrid Riecken/For The Washington Post)

Hayley Plack’s train had just pulled away from a downtown D.C. station Friday morning when she glanced at the ring finger of her left hand.

No, she thought. That can’t be.

Her engagement ring was gone.

In a gray dress and black flats, she pounced to the floor of the Metro car, crawling around as her eyes frantically searched for a sparkle. Nothing.

She got off at the next stop and called her fiance, Andrew Frank. On Thanksgiving, 22 days earlier, he had dropped to one knee and presented her with a 1.1-carat oval diamond that belonged to his grandmother. “Mommas,” as Frank called her, had left it to him so that one day he could slip it on the finger of the woman he loved.

The engagement ring that Hayley Plack lost that was later returned. (Astrid Riecken/For The Washington Post)

And now it had slipped off.

But maybe it hadn’t, Plack told herself. Maybe she had forgotten to put it on that morning, and it remained on her night table. Frank, a hospital rehab technician, didn’t answer the call. He was asleep in her Adams Morgan apartment.

Plack, 27, took a train back to Farragut North, where she first got on. She searched the platform. Nothing. She rushed up the escalator to the street, retracing her path back to the bus stop. Nothing. She hailed a cab and on the way home sent an e-mail to her boss at the National Gallery of Art, where she works as a program assistant: “I will be in late today. I’m dealing with something at home.”

She burst through the bedroom door. “Andrew” she shouted, “have you seen my ring?”

Not on the night table. Not in the sheets. Not between the mattress and box spring. Not under the bed. Not on the hardwood floor. Not inside the lining of her black puffy jacket with a hole in the pocket that fleetingly offered her hope.

She sobbed. Frank, 32, tried to soothe her anguish.

Maybe someone would find it, he said. And maybe, somehow, that person would find them. “Not everyone in the world is a criminal,” he told her.

Andrew Frank and Hayley Plack are seen moments after he proposed at her parents’ home in Baltimore on Thanksgiving night. She is wearing the ring later lost and recovered. (Family Photo)

But Frank didn’t believe his own words, and he didn’t say what he really believed.

“It’s gone,” he thought. “Forever.”

‘Let me see the ring’

At almost the same moment Plack called Frank, a slender British man with glasses emerged from an apartment building four doors away from hers.

Siranjan Kulatilake, 55, walked down his steps, and there, on the sidewalk, he spotted a diamond ring.

The band was so small he wondered if it belonged to a child. Puzzled, Kulatilake hooked the ring onto a lanyard that held his keys. Then the part-time dog walker headed to Dupont Circle where a pair of Shih Tzus were waiting for their morning ramble.

As Bonnie and Buster sniffed at bushes and fire hydrants, Plack and Frank were methodically scanning the sidewalk between their front door and the bus stop, passing Kulatilake’s building over and over.

They posted pleas for help on Craigslist and a local blog. They called the police and filled out a report. They called pawn shops and hoped a thief might have already sold it. They called the insurance company and imagined how suspicious their story must sound.

The couple had met three years earlier. They went on countless ice-cream dates (chocolate for him; anything for her) and quickly adopted each other’s passions (his for the Orioles; hers for museums).

Before he proposed, Frank asked Plack if she wanted a new stone instead of his grandmother’s diamond. She insisted on the heirloom.

Now, suddenly, Plack dreaded the holiday parties that she had so long looked forward to. Let me see the ring, people would ask. She would have nothing to show them.

Even worse, she would have to explain what had happened to Frank’s mother, who treasured the ring just as much as she and Frank did. There was a love story in its facets.

When Frank’s grandparents married in the late 1930s, his grandfather, Bill Williams, couldn’t afford an engagement ring for his wife, Genevieve. Years later, after a career as a federal auditor, he became friends with a gemologist at the Smithsonian. Williams told the man to find him something special before the couple’s 40th anniversary.

Genevieve almost never took that diamond off, her daughter, Wendy Frank, recalled.

In 1998, with Bill suffering from dementia, the couple decided to move from their house in Alexandria to a retirement home in Baltimore.

One day while Genevieve was at the grocery store, a cleaning crew came to haul away what the couple no longer wanted. Bill directed them to the basement, and among the items they threw away was an empty paint can in which she had hidden every piece of expensive jewelry she owned — except the ring.

Frank didn’t know his grandmother wanted him to have her diamond until after she died in 2012 at age 99.

Desperate, he and Plack searched their trash, picking through wet coffee filters and rotten lettuce. They re-rode her bus route and got a number for the people who clean the vehicles. At the Metro station, they found the manager.

As riders walked past, Plack broke down.

“I’ll pray for you. Keep your faith in God,” the manager told them. “Let’s hope a godly person finds it.”

‘What do I do with this?’

Kulatilake, who describes himself as an atheist, returned to his apartment and examined the ring.

“What do I do with this?” he wondered. “It’s obviously precious to someone.”

The self-employed mass-transit consultant wanted to find that someone and return the ring to her. The nickel-sized piece of jewelry reminded him, he told his wife, of an incident from his youth.

Around age 10, his father, a Sri Lankan-born surgeon, gave him a Parker 61 fountain pen. The gift wasn’t just expensive. For reasons he can no longer remember, it also had deep sentimental value to his dad.

Kulatilake recalled the moment he realized it had disappeared. He, too, was on a subway train, the London Underground. He searched his bag and the pockets of his school uniform. He went to the station master and the lost and found.

He never recovered the pen, and more than 40 years later, it still haunted him.

Kulatilake, who has lived in the District for about 15 years, placed the ring into a vase for safekeeping. He and his wife discussed how they might find the owner. The Internet? Local jewelers? He had no idea.

The next morning, on her way back from the farmers market, his wife saw one of the fliers Plack had taped up around the neighborhood.

“LOST ENGAGEMENT RING,” it said. “***REWARD WILL BE OFFERED***.”

Plack and her mother had just finished wedding dress shopping and were on their way to a florist in Annapolis when her cellphone rang. She ignored the call, but listened to the voicemail.

“Hey, Hayley,” Kulatilake said in his clipped British accent. “I think I found your engagement ring on the street. Give me a call if you get a chance.”

She screamed, then called him.

She asked where he had found it. He told her. He asked for a description. She gave him one.

But before Plack got her ring back, before she texted her fiance a message that ended in 11 exclamation points, before their mothers cried, before she once again looked forward to holiday parties, Kulatilake asked her an important question: “So you said a reward would be offered?”

Plack panicked. Yes, she told him. How much do you want?

“I don’t want the reward for myself,” he explained. Could she make a donation to the Washington Humane Society? Even $50 would suffice.

That night, they posed together for a photo.

In Kulatilake’s right hand was a check to the organization for $400. On Plack’s left was the ring.