TORONTO -- In "The Inevitable Defeat of Mister & Pete," powerhouse vocalist Jennifer Hudson disappears into an entirely unfamiliar role as a drug-addicted prostitute and absentee mother, her eyes drooping, her hair a sweat-sopped pile, her tattooed arms pocked with syringe scars.

And Alicia Keys, who executive produced and scored the film, couldn't believe how completely her friend dived into the unflattering performance.

"This is what defines Jennifer Hudson as an actress, this film here. This is a defining role for her," Keys said in a recent telephone interview from New York. "She's a drug addict and she is in pain and she feels hopeless, and she's also trying to somewhere inside of there raise a son even though everything is pointing to just this discouragement.

"She did an amazing job. It was totally unvain. Totally selfless. She went all the way in. ... We're already great, great friends, but I admire her to a whole other degree and level for being brave enough to take a role that takes you that far away from yourself.

"Like, she aced this thing," she added.

Keys speaks with an uncommon passion for the acclaimed film -- which is out on DVD in Canada on Tuesday -- because she spent five years nurturing it to the screen.

The gritty drama tracks Mister (Skylan Brooks), an endlessly feisty 13-year-old who is left to fend for himself (along with his nine-year-old compatriot Pete) for one long, hot Brooklyn summer after his mom is hauled off to jail.

Keys, 33, first discovered the script from Michael Starrbury when director George Tillman Jr. ("Men of Honor," "Notorious") brought it to her attention a half a decade ago.

Though at the time she had no experience either producing or composing a film soundtrack, she was so moved by the story she knew she had to get involved.

"When I read it, I was blown away," said the serene, friendly Keys. "(It's) almost tragedy, it's triumph, it's got comedy but realistically. You find yourself as you're watching it, you're laughing, you're crying, you're rooting for these boys.

"I fell in love with it," she added. "I knew I wanted to score it. I wanted to be part of it. So then I set off on the journey of how to make it real."

The 15-time Grammy Award-winning "No One" hitmaker has transitioned smoothly to screen before -- most recently in "The Secret Life of Bees," "The Nanny Diaries" and "Smokin' Aces" -- but chose not to take a role in the unflinching coming-of-age story.

Brooks' resourceful Mister harbours seemingly unlikely acting ambition, and at several points in the film recites a monologue he's memorized from "Fargo" (a "hilarious" movie he eagerly points out is about "these Minnesota people with funny accents").

Keys grew up in the once-rough Manhattan enclave of Hell's Kitchen and personally related to both Mister's hardscrabble surroundings and his show-business dreams.

"That part really resonated with me -- him hanging onto this one wrinkled postcard of an audition in L.A.," she said.

"I definitely understand that feeling of having a dream, having something to hold onto, something that you're working for, and it gives you the desire to go beyond your circumstance.

"I think one of the strongest things that the human spirit needs (is) something that says: I can get up again today because this just might happen for me," she added. "We all need that and we all have that inside of us."

Though it received only a limited theatrical release, "Mister & Pete" earned enthusiastic critical praise. The New York Times called Mister "one funny, sad kid in one funny, sad movie," while the L.A. Times cheered the film as a "moving bit of mischief and mayhem that will break your heart, give you hope, make you laugh, possibly cry."

With due respect to those critics, the rave that most moved Keys came from Michelle Obama, who hosted a screening of the film at the White House in January.

"She fell in love with the film," Keys said.

Obama followed the presentation with a group discussion about improving educational access in underserved communities.

This surprised Keys. Though the film is bookended with references to Mister's struggles in school, during the vast majority of its running time he's winding around the sun-baked projects, his education seemingly the farthest thing from his mind.

"It's so interesting because the film is about so much. It's a story about poverty, it's about addiction, it's about the different social issues that different neighbourhoods have in America -- neighbourhoods that I grew up in and am very familiar with," Keys said.

"I think what really connected to (Obama) was the education initiative. When she says that this is what she wants to work on in this term, and that this is her favourite film of the past year, I think one of the words that came up after the screening was the word 'resilience' -- and finding the ability (and) drive to pull yourself through a circumstance that might not be so easy.

"What was so incredible," she added, "was I didn't quite think of that issue when I went through this whole process of producing (the movie). But to then give it that context as well, just really showed me again that when you do a piece of art, it is supposed to make you think and it challenges you. That's what this film did."