On a trip with my family to Lexington and Concord, my father and I stood on the field where American revolutionaries made a stand against the British. As we looked out, he said to me "can you imagine standing here at sunrise, scared out of your mind, knowing that British troops were marching toward you?" In that moment, we were there and felt something like what we imagine the volunteers who helped build the United States felt. It was something larger than the moment itself.
People use the word "haunted" all the time without an explicitly supernatural meaning - even if you don't believe in ghosts, it's not hard to see how the history of some places might hang over them, our understanding of what happened there superimposed on the place in front of us like an overlay. Why else would a musician like Trent Reznor rent the house on Cielo Drive where the Manson family committed one of their most gruesome murders? Why else would you keep bomb-pitted ruins standing around the memorial to the Murrah Building bombing? Why else leave Dachau standing? Even if you don't believe in ghosts, our understanding of a place gives it power, evokes memory and history and understanding.
In Session 9, this juxtaposition between past and present creates a place where ghosts - supernatural or otherwise - live, and uses that ambiguity to tremendous effect.
Gordon Fleming runs a small asbestos abatement company. He and his wife have a brand new baby girl, but money is tight. He keeps getting outbid on jobs - he's a man of integrity, wants to do the work right, but that means losing work to people who are willing to do it quicker and cheaper. This is his life's work - he learned from his father, and as one of his coworkers puts it, "fiber is his life." This is what Gordon knows how to do, and he's fiercely proud - he doesn't want to work for someone else, he wants to run his crew and make sure the work is done right. But something has to give because integrity and pride don't put food on the table or pay the doctor bills when his daughter is sick. So when he finds out about a job cleaning up an old mental hospital, he puts in a bid to do the work in a week - maybe half to a third of the time anyone else is offering. It's going to be punishing as hell, but Gordon has men to pay and mouths to feed.
The building has been more or less abandoned for decades, occasionally visited by junkies, vandals, or the homeless. It lies in ruin, much of the old equipment sitting, rusted, where it was left when the hospital was vacated. Time stopped here, but everything continued to rot. The place is full of asbestos - in the insulation, in the floor tile - and extensive safety measures will have to be taken. Clean suits, decontamination, negative air pressure. Gordon brings in four more guys for the job. They have mere days to do the work of weeks, everyone is feeling the pressure here. It doesn't help that most of the crew members have pasts together - buried grudges, hidden resentment. They haven't even started work and already everyone is stretched tight.
The hospital doesn't help - it's creepy as hell, piles of old, abandoned equipment, patient's personal effects, Inexplicable things like a room plastered in photographs and children's drawings. Hidden stashes of coins. And in the basement, a room full of files, and recordings of therapy sessions with patients. Work competes with the distractions the hospital has to offer, and one by one the men start to lose focus. And then one of them disappears. And then everything falls apart.
Over the course of the movie, story layers upon story, history layers upon history, the past layers upon the present, and voices become more and more important - remembered conversations, simple questions, the recorded accounts of a patient named Mary - they start off innocuous enough, but as events play out, and the strain of where these men are and what they are doing begins to claim lives, those conversations and simple questions become disturbing in their implications, the recordings of Mary's voice pitch closer and closer to anguish and hysteria, and in the end, this place where the past and present mingle, those voices are silenced. The people who most desperately want to be heard cannot be, and those who most want to go home can never do so again. The past makes the hospital a prison, and it's ultimately just a matter of which set of ghosts you think was responsible for the whole thing.