The film Herman’s House begins with the sounds metal doors slamming and an aging man’s phone-muffled voice describing his surroundings. "I can only make about four steps forward before I touch the door, and if I turn in an about face at any place in this cell I’m going to bump into something. I’m in a cell for 23 hours a day. I’m used to it and that’s one of the bad things about it."

Herman Wallace is a 70-year-old man who’s spent every day of his life in prison since he was convicted of bank robbery in 1967. For the last 40 years of that time, he’s been confined to a solitary cell. Wallace was sent there when he and two other prisoners–the Black Panther Party members now known as the Angola Three– were alleged against nearly all evidence to have killed a guard in Louisiana’s Angola Prison.

Herman’s House casts a nearly magical tale of Wallace’s collaboration, and friendship, with a free-spirited young artist named Jackie Sumell who heard of Wallace at a lecture and wrote him a letter asking, "What kind of house does a man who has lived in a six-foot-by-nine-foot cell…dream of?"

What’s remarkable about Herman’s House, and the artistic collaboration that it follows, is that we learn about an Angola solitary cell by focusing entirely on its opposite. Not once in the film is there a shot of Angola’s interior. Wallace is heard but never seen, his voice plays over abstracted animations of prison bars. The house that he and Sumell design is a sprawling one with a pool, portraits of revolutionaries on the wall and a bright yellow kitchen. Sumell builds it as a scaled model and shows it in art galleries along with a right-sized wooden model of Wallace’s cell. That’s the closest we get to the inside of the prison, but in some small way we can feel the prison’s interior precisely through the material of Wallace’s longing–his dream house, his sister’s house, the neighborhoods of New Orleans. By hearing a story about a jailed man’s dreams of freedom, we begin to feel the horror of the prison.

"The only way I could get him out of prison," Sumell says, "was to get him to dream."

Over years of letters, Wallace does.

"In the front of the house I have three squares of gardens; the gardens are the easiest for me to imagine," Wallace said. "And I can see they would be full of gardenias, carnations and tulips. This is of the utmost importance. I would like my guests to be able to smile and walk through flowers all day long."

Angad Bhalla is the films director. At a screening last night at the opening of the Harlem International Film Festival he told me, "It’s really a film about the idea of a prison because in some ways that’s what we’re up against."

"I am always trying to think about ways we can reframe things, ways to communicate with new people."

It should be no surprise that Bhalla’s film is such a success at talking to broad audiences. It’s framed through ways of seeing that people who’ve never been inside a prison, and may have spent little time thinking of them, people like Sumell, a young artist with an idealistic heart, can understand. It’s not a story about the horror of prison, about the history of mass incarceration or the growing body of research about what solitary confinement does to the minds of its victims. It’s a story about what a man’s life might be like if he were free.

Over 81,000 men and women are shuttered in solitary confinement in the United States, according to the federal Bureau of Justice Statistics, and Wallace’s attorney says his client has been there longer than anyone. Though the evidence of the murder was thin or "lost" and witnesses, even the dead man’s wife, have come out against the Angola Three’s endless confinement, two of the three men remain in solitary, re-relegated there every three months by a rote administrative review.

Until recently, cells like the one Wallace is in have been invisible to those who are not thrown in them. They’re made so on purpose. Just a few days ago, on Monday, I interviewed a California woman whose uncle is in "the hole" in a federal prison. That’s all she knows now because he stopped calling, stopped writing, because there’s been no word of him since he was sent there. He’s basically been disappeared.

"Solitary confinement is torture and it is destroying people," Soffiyah Elijah of the Correctional Association of New York said last night in conversation on stage with Bhalla. Her group advocates to end the practice of disciplinary confinement in New York. But change is slow. According to a recent article in The Nation about solitary in New York State, "On any given day, there are about 4,500 men, women and children in some form of isolated confinement in New York State prisons. (In New York City’s jails, run under a separate system, there are close to 1,000 more.)" Just about three miles as the crow flies from the Wednesday evening screening, in New York’s Riker’s Island jail, the number of beds for solitary confinement has grown by nearly 40 percent since 2010.

Advocates and a growing crop of journalists have made strides to make solitary confinement visible, to show the country that it is a kind of cruel and unusual punishment with no place in the country’s criminal justice regime.

Yet in all this exposition of the problem of mass incarceration and solitary confinement, those cast into these holes are too often treated as dead souls, so tragically desecrated by their isolation that they are barely still living. Indeed, solitary confinement does rip it’s victims apart. We hear of men dying solitary, their screams unheard. But Herman’s House insists on life and the living that still exists inside.

"I wanted to look at prisoners as people where people live," Bhalla told me. "This is fundamentally what prisons are. Rather than just looking at them through the lens of crime and punishment–what did they do and why are they there?–I want to look at them as places where life happens."

Even as Wallace’s body has begun to decline, his age and years of wretched immobility eating away at his muscles, his hearing and his strength, he lives deeply through the pure force of imagination. As the film progresses, Wallace decides that his dreams should made real, and Sumell embarks on a journey to build the house. Wallace tells her to erect the house in New Orleans to be used as a community center for kids at risk of going to jail. Sumell moves to New Orleans and searches for land.

But the trials and inequities of life outside prison walls catch up with them. Herman’s dream house meets building ordinances and the land Sumell believes she’s found for the building is scooped up by a New Orleans developer. Life outside is not a dream. It is real, just as life inside the prison is real. And as the film ends, Wallace’s latest appeal is denied. He will not be released, and we’re left with nothing but the relationship that these two unlikely friends have built. Through that, and through their game of imagining, we meet Herman Wallace, fully alive.