Octavia Spencer almost passed on one of the most acclaimed movies of the year so far — “Fruitvale Station.”

The film, released in select theaters last week and opening wide this weekend, tells the true story of Oscar Grant, an unarmed black man fatally shot by a white police officer in an Oakland, Calif., train station early on New Year’s Day, 2009. The officer was convicted of involuntary manslaughter and served 11 months in prison.

Video of the shooting circulated widely on social networks, and a snippet of it shows in “Fruitvale’s” opening minutes. It’s that footage that made Spencer initially decline the pivotal role as Grant’s mother.

“In seeing the video, I said the only thing that I could offer this role is anger. And I think this situation requires much more than that because it already has a potential to be explosive,” said Spencer.

But she read the script — which chronicles Grant’s last day — and was moved.

“It restored Oscar’s humanity in a way that the trial, and all of the recriminations around it, had basically taken from him,” Spencer said in an interview at this year’s Cannes Film Festival. “So I wanted to be a part of it for my nephews … all the young men of color whose lives sometimes feel more expendable in a way. … They’re so many reasons.”

“Fruitvale Station,” which stars Michael B. Jordan as Grant and was helmed by first-time director Ryan Coogler, won the Grand Prize and the Audience Award at the Sundance Film Festival, as well as “Prize of the Future” at Cannes. It has drawn critical praise and prompted comparisons to the racially charged death of another young black male, Trayvon Martin.

“Fruitvale” is also generating early Oscar buzz.

It was Spencer’s first high-profile role since her Academy Award-winning turn as a feisty maid in the racial dramedy “The Help.” The actress, who was virtually unknown before starring in that blockbuster, admits that the success of that performance changed the way she considers future roles.

“Before, you just take what you need to do to survive. I now want to take roles that challenge me and stretch me as an actor. So this was a beautiful story,” said Spencer.

But Spencer was more than just a hired actor on “Fruitvale”; she was also one of its producers, along with Oscar-winning actor Forest Whitaker. Coogler said in some ways, she was like the film’s fairy godmother.

“While we were shooting, some money fell out, and we were in a lot of trouble,” he said. “She really rolled up her sleeves, and went around to all her friends as a producer to help make sure the movie continued to get made.”

One of the people she reached out to was Ahna O’Reilly, one of her closest friends and a co-star in “The Help.” O’Reilly plays one of the people who touched Grant’s life on his last day alive.

“She called me and was like, ‘I’m doing this movie in Oakland, we need you to play this role, can you please come do it?’ I was like, ‘I would do anything for you. Of course,’” recalled O’Reilly. “And then I read the script, and I was like, ‘I’m coming to do it. Don’t let anyone do this because the script is so moving.’”

One of the film’s more heartbreaking scenes is when Grant’s mother visits her son in prison during a flashback scene. Spencer said she felt a special duty during the film to Grant’s mother, whom she met with before she filmed the movie.

“I told her I wasn’t going to try and mimic her, I just wanted to represent her as a real woman, as a mom, who has basically suffered this tremendous loss, and she was amazing. She was guarded at first, but she should be,” Spencer said.

“There were all these recriminations and her son was vilified in a way that people didn’t get to see him or know him,” Spencer continued. “That’s what was so beautiful about Ryan’s story. … It just presented (Grant) warts and all to the public and that’s a big responsibility.”

Spencer said she’s gratified by the positive response to “Fruitvale,” and by having another strong role in which to shine — a longstanding problem for African-American actors. Spencer acknowledges it can be a “challenge,” but one she’s up for.

“If you wait around for other people to bring you interesting things you won’t discover the riches of the world. So I like it,” she said. “I like being able to go out there and find things. And having jewels like ‘Fruitvale Station’ find me.”