"Sound of Hope: The Story of Possum Trot" seemingly came out of nowhere when it surged during the extended July 4 weekend, nabbing seventh place at the box office and earning $6.7 million in 2,200 movie theaters nationwide.

But the big-hearted story that won solid reviews (81% fresh on Rotten Tomatoes) and audience plaudits (97% positive audience score) has been decades in the making.

Starting in 1996, the Rev. W.C. Martin (played by Demetrius Grosse) and his wife, first lady Donna Martin (Nika King), crusaded for members of their 100-member Bennett Chapel Missionary Baptist Church in Possum Trot, Texas, to adopt the most difficult-to-place children in the overwhelmed local foster care system.

The Martins, who already had two biological children, adopted four, spearheading a miraculous 22-family congregation effort to adopt 77 children. The couple, who appeared on "The Oprah Winfrey Show," worked for years to have a movie made about their real-life events, Martin tells USA TODAY in a joint interview with Donna, his wife of nearly 47 years.

Join our Watch Party!Sign up to receive USA TODAY's movie and TV recommendations right in your inbox

Need a break? Play the USA TODAY Daily Crossword Puzzle.

"There were so many hoops and hurdles," he says. "But we knew when God got his hands on this, we were going to come out victorious. This is the feature film of our true story. It's the real McCoy."

Distributed by Angel Studios, the faith-based studio behind last summer's surprise hit "Sound of Freedom," "Sound of Hope" was written and produced by the husband-and-wife team of Joshua and Rebekah Weigel, who moved to East Texas to distill the story from the actual people and events. The movie, directed by Joshua Weigel, is referred to as "inspired by" the true story in promotional material.

Martin, 77, and Donna Martin, 68, discuss what's true in "Sound of Hope."

Donna Martin was inspired to adopt after the death of her beloved mother

Donna was compelled into action when her beloved mother Murtha, a matriarch who had raised 18 children, died in 1996. As seen in "Sound of Hope," Murtha's loss was devastating.

"I had such unbearable pain that day. I said 'OK, God. Either hear me out or let me die,' " Donna says. "And the Holy Spirit said, 'Think about those other children out there that do not have what you had with your mother.' I was overcome with such warmness. I walked back into the house, picked up the Yellow Pages and called an adoption agency."

The Martins adopted four kids and led the congregation to follow: 77 children found families

The Martins, who had two biological children of their own, Princeton and La'Donna, first adopted a brother and sister, Tyler and Mercedes, as seen in the movie. Then they adopted two more, Josh and Terri.

"When we started, that was a struggle," says Martin of bringing the four new children into the household. "Because we had to transform children's minds and hearts and attitudes. We were out of our comfort zone."

The reverend preached on the mission of making an impact and 21 other families followed up with adoptions. "We all became one extended family," he says. "Adoption is not an easy thing, but it's a rewarding thing."

Some incidents in the movie were dramatized, representing the painful pasts these children had experienced in their previous homes and the difficulties they faced adjusting to their new family.

"We didn't want this to be a Cinderella story because it's not. It was challenging," says Donna. "We wanted to demonstrate what these children's trauma and loss and rejection looked like before. And at the end of the day, through determination, prayer and unconditional love, how they have benefitted. We all have."

All six of the Martins' children are now adults: Princeton, 44; La'Donna, 37; Terri, 34; Josh, 31; Mercedes, 32, and Tyler, 29.

"They still have their struggles, they still have their demons. But they are doing well," says Donna. "So our message to the world is 'Don't give up on these kids.' Give them more than second chances. Jesus gives us all chance after chance."

"Every last one we adopted has grown, and I'm so happy for that," says Martin, who was in charge of preparing the food for a reunion of the church families, pictured at the end of "Sound of Hope."

"I earned my keep that day, cooking 28 slabs of ribs and frying about 80 pounds of catfish," he adds. "Then I was up early and preaching on Sunday morning."

Texas social worker Susan Ramsey was real and 'a gift from God'

Social worker Susan Ramsey (Elizabeth Mitchell) spent her career working tirelessly to place and protect foster children. Meeting the Martins and the families of Possum Trot and helping facilitate their adoptions was an extraordinary success story. Ramsey earned the Child Welfare League of America's Outstanding Service Award in 2000 before dying of cancer in 2002.

"Susan was a gift from God," says Martin. "I tip my hat to her, even today."

"She was one of the angels in this movement," Donna adds.

At the "Sound of Hope" premiere, Donna emotionally thanked Mitchell for bringing Susan to life on the screen.

"It was like Susan, our Susan, was right there with us," says Donna.