A long-lost box of treasures found in one man's attic has unlocked a decades-old love story, ending in an unexpected surprise for a family that for the past roughly 70 years hadn't even realized anything was missing.

Joshua McKinney, of Casnovia, Mich., was removing old insulation in his home's attic on Jan. 25, when he found a stack of old love letters from the World War II era.

"He was scooping up old insulation to put the new insulation down, and while he was scooping, the letters just fell," Christina Frein, the now very grateful grand-daughter of the man who'd written the letters, told GoodMorningAmerica.com of McKinney's discovery.

The findings were wrapped in a dainty, disintegrating pink ribbon and included a birth certificate from 1942 for William Kissel, Frein's father, and a marriage certificate from 1941 for Edward and Virginia Kissel, Frein's grandparents.

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Unsure of how these delicate old documents had ended up in his attic, McKinney and his sister decided to try to find the family these letters had once belonged to. They alerted their local news station, which shared the remarkable discovery on social media, and within four hours of the post circulating around the western Michigan area, Frein, who lives about an hour away in Muskegon, took notice.

"He found these on the same weekend my uncle, my dad's brother, passed away," said Frein, a complete stranger to McKinney. "It was really freaky, like my dad was trying to talk to me."

As soon as she heard about the discovery, Frein traveled to collect the sentimental pieces. But what she found when she got there was even more than she had expected.

"I thought I was going to retrieve stuff of my father's, but to see all these things, love letters from my grandfather to my grandmother, that was a huge bonus," Frein explained.

Edward Kissel, her grandfather, passed away before she was born.

"I didn't grow up with him, so this is a whole love story we never even knew," said Frein. "When my grandma remarried, she never really talked about him."

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After thanking McKinney for realizing how important these would be to someone and taking the time to track them down, Frein took the letters home to show her mother, Shirley Kissel. This was the first time Shirley was given a chance to get to know her husband's father, whom she herself had only met once before his death.

Although the letters did reveal many heartfelt stories between the family's lost loved ones, one thing, however, was still a mystery.

How could these possessions end up in a home in Casnovia, a place her relatives had never lived?

Frein did a little more digging into the area's past. It turns out McKinney's house was indeed her grandparents'. However, when they lived in the home in the 1940s, it was part of a community located in Muskegon.

"My grandparents moved out of the house and the projects were eventually sold," she explained. "All the houses were separated and relocated, literally picked up and moved to different locations. Their particular house was moved to Casnovia, which is where Joshua lives now."

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At long last, after years of separation, Frein and her mother said they are thrilled to have the letters back where they belong - in their possession.

"I love touching them, knowing that my grandparents had their hands on them," she said. "Knowing I was standing in the house my dad grew up in when he was little brings chills down my spine."