Inspired by the story of the 20th Century's best-documented exorcism, Requiem features Sandra Huller as a 21 year-old convinced she is possessed. Carol Murphy talked to director Hans-Christian Schmid about this highly unusual project.

Requiem, directed by Hans-Christian Schmid (Crazy, 23, Distant Lights) is derived from the story of the most well-documented exorcism of the 20th Century.

In her feature debut, Sandra Huller plays the part of Michaela, a 21 year-old who is given the chance to leave her cosseted, deeply religious home to go to University after a lifetime of seclusion in 1970s rural Germany. Her stern mother and gentle but weak father fearfully let her go after supporting and suffocating her through her battles with what is understood as being epilepsy.

Initially Michaela flowers at university but her psychological health deteriorates when she sustains a series of grotesque mental attacks. Her desperation to be normal, coupled with as series of ill-informed decisions taken by her friends and family, lead Michaela to seek help from the Catholic Church rather than addressing her condition rationally. In the end she is willingly exorcised, believing that she is possessed and that exorcism is her only route to salvation.

In the opening scene we see Huller as Michaela cycling up a steep hill in her rural hometown. Many of the elements which consummate Michaela's character and circumstance are clear at once. Huller's incredible performance is the index of Michaela's extreme energy, her power and will to struggle, her otherness, but also her dreadful fate.

Carol: It is interesting the similarity between making films and having a vocation.

Hans-Christian: I don't know if I have that, but I like very much to be able to make films. A vocation is when you cannot imagine living without that. I could.

How did you become interested in the story which led to the making of Requiem?

I come from a place for pilgrims, so I grew up with all kinds of religious behaviour, so I was always interested in that. I also made a documentary about the pilgrims, but initially I became interested in a report on a pilgrimage to Klingenberg. This is where the Catholic student Anneliese Michel died in 1976 of malnourishment and exhaustion after a series of several dozen exorcisms. I was amazed that, even twenty years after her death, she is still venerated as a martyr in Klingenberg by pilgrims from all over Europe.

But the first time I read about Anneliese Michel, this girl wouldn't leave the family home, I just wanted to understand how it could be that someone like her asks for a priest and for an exorcism, and how could it be that all the people surrounding her and loving her have no possibility of actually helping her.

I became interested in her story, read a great deal about other exorcisms in the 20th Century, and began to write a treatment. That was nearly ten years ago, and the story hasn't let go of me since.

Requiem in its turn is above all the psychogram of a young woman who finds herself in an extreme situation. Today you don't have to convince any open-minded person that an exorcism is not the best way to help someone who is mentally ill. I was fascinated by Michaela's extreme situation: a young woman surrounded by her parents, siblings, friends, who all want to help her. Yet the gap that the illness has created between them is too great to be bridged.

Why did it take so long for the film to be made?

I had taken a different approach at first. I couldn't find the courage to put the young woman at the centre of my story, so I chose her boyfriend instead. Then I worked at Distant Lights until someone told me about Bernd Lange, who studied at the Filmakademie Ludwigsburg, and who was also working on this topic.

Was it difficult, at the writing stage to acquire distance from the true story? Obviously Requiem is not a documentary and it is not attempting to be a straight adaptation.

It was difficult, and I only came in on the last two drafts, but I know that Bernd, the writer, wanted from the beginning not to be that close, because we both thought it was not the kind of a film we wanted to make. It is hard because I think you have to overcome a point as a writer where you stop collecting information and there is a lot about this case. It is the best-documented case of exorcism in the last century. You have to put it aside and rethink what you want to tell. And I think this is the really hard part.

And when did you realise that you had reached that point?

Have we reached that point?

Before you started to write and direct the story, I mean.

Yes, Bernd took a lot of time. It was his final work at film school – almost three years. It is not that easy to start making things up because you feel obliged to the family somehow and you have to balance that. You want to tell a story that works; you want to keep close but also get away from real events. You know, I think we achieved it when we did not know how to improve it anymore. You come to a point where you see that every change means some good and some bad effects. I never think a script is really completed until the last edit in the editing room.

Does the responsibility you have to the story and to the relatives who are still alive worry you at all?

It did worry me a lot, because I knew at one point they would hear or see the film. When we finished shooting I contacted them and I knew that I was quite safe from a lawyer's point of view, but I wanted to tell them that there was a film. But I did not want them to tell me how to edit the film or how to write the script, so that is why I contacted them afterwards. The younger sister of Anneliese was great. Like the family she was a bit angry at first, but she started to like the script and the film and in the end she came to the Berlin Film Festival and it was very important for me to have that.

The film is engaging but also entertaining. Does that worry that you are using a tragic story in order to entertain?

It is not worrying me because I think Bernd and I made the film not in the first place to entertain, and we knew that we wanted to end up with a story that will to do more than just entertain.

How did you find Sandra Huller to play the central part? She's fantastic!

Very very easily. I worked with a casting agent. Sandra was the first actress who was proposed to me. I could have said yes, but I didn't. And then after three or four weeks of casting I was very sure that she was the right. And she changed the way I thought about the character of Michaela because she has such physicality and power that I realized helped the story. When I first thought about the casting I thought of having someone thin and pale, someone you would believe would fall for all of these things. So it was really very good.

When I read an interview with Sandra Huller she was asked about when she found the key to the character, and she said that she hadn't found it and that she used the script like an instruction manual. I thought that was very clever and strong!

It was hard for me to work with Sandra in the beginning. With the films I made before there was a very long preparation time with actors playing very similar roles who read all the articles and everything we had surrounding their character. Sandra did not. She played in the theatre in Basel in Switzerland the night before we started shooting. She didn't want to have too close a contact with the real character, which I can understand very well now, but when we started I felt strange because I did not understand that from the beginning.

In Requiem I feel that the tragedy of Michaela's story is in the minor circumstances that lead to her downfall. When she has her first attack in the film she is holding the rosary beads that her mother gave her, and so the attack takes on greater religious symbolism when it is not necessarily the case.

Well, the rosary beads were a present from the mother. These are all Bernd's deliberate script decisions and he found ways to show the relationship between Michaela and her mother without having long dialogues. And I cannot see the mother as an unloving mother. She cannot show that she loves and cares, but she is also a victim herself as she is from a generation who went through the war and who had to look after the family and are very harsh somehow. The father, on the other hand, takes the place that is left for him in the family constellation, which is trying to avoid conflict and making it worse.

Michaela pushed people back as well.

Very much.

The exorcism scene felt incestuous.

I was thinking that it could be compared with a rape. It is more or less women that are exorcised - hardly any men. That has to do with it, I think. It is more or less the priest who executes that, but the family is very much involved in it.

And these women who are being exorcised believe that they are possessed.

I am absolutely sure that they believe that. A pilgrim who goes to Lourdes or Fatima thinks that they get something back from it – like a give and take situation. And I think these people also believe in a very concrete God and in a concrete Devil.

There is a self-loathing and a masochism also.

Definitely. And in the end this is the only way for a family in a small village with a daughter who is psychologically ill to have a solution that is fine for everyone, apart from the fact that the girl dies. The death of the girl is part of this martyr solution. She follows Christ in the way that he suffered, and I think that this is actually something that she believed in very much. In her death she is picked by God and is someone very special.

How did you settle on the '70's period look of the film, and how does this relate to the story?

I was working with the DOP and the set designer for the second time; we used a documentary-style of shooting with the film before, and we really liked that way of working. It gives me a lot of freedom with the actors. That is the first thing. The other thing is that we thought about giving it a realistic look. How did films in the '70s look – the zoom, the grain, the colours? The DOP I am working with is very open to experiments and he is eager to try out different things. And the set designer was very careful with colour. But we also tried to hide what we did so that it did not have the look of something deliberately set up for a film.

How did you approach filming Michaela's actual attacks? I was glad that you didn't make a filmic rendition of what she was seeing or feeling at the time of the attacks.

Why were you glad that we didn't do it?

Because I have seen it so many times and it can be naff.

Okay, so you have exactly the reason why we didn't do it! In 90% of the times when you see that it just doesn't work. I think it is pretty clear how you can approach these scenes. I provided Sandra with videos of people who have these epileptic strokes, and she didn't want to see them. She asked, 'Can I play the way I want to and then you can tell me if it works or not?' And I said, 'Yes of course we can have it this way.' And what I saw in the videos was that there is no specific way – if you have a stroke it can be full body, only left hand, it can be this and that. So my only way was to watch Sandra when she was doing it and ask do I believe her or am I watching an actor? And I believe her.

Requiem is Sandra Huller's feature debut. She won the Best Actress Award at the 2006 Berlin Film Festival for her portrayal of Michaela. Requiem won Best Film at the 2006 Sitges Film Festival.

Requiem screens at Dublin's IFI from 8th December 2006.