Smoke billows from a herb burner filling the Spirit Room with an eerie haze.

A woman stands over Hollywood actress Megan Duffy chanting and shaking a rattle carved with a head inspired by shamanic art, as her client lies motionless on a narrow bed.

The tension in the air is thick as the 'healer' places an ornate dagger on Duffy's wrist and, breathing deep, rapid breathes, summons 'higher beings' from the spirit world, asking them to rid her body of evil demons.

The woman carrying out the 'working' is Rachel Stavis - the world's only non-denominational Exorcist.

And in a television first DailyMailTV was invited to witness Stavis carry out a real-life Hollywood exorcism.

We watched as Stavis worked on actress Duffy - best known for starring alongside Elijah Wood in 2012 horror movie Maniac - ridding her of an evil 'entity' that she believes has attached itself to her.

Sister of Darkness: Rachel Stavis reveals to DailyMailTV how she has performed exorcisms on Hollywood moguls, Oscar winners and politicians and for the first time opens up one of her exorcisms to the cameras

Exorcism: Rachel Stavis, performs an exorcism on actress Megan Duffy in her Studio City home - her first ever televised casting out of evil spirits. She tells DailyMailTV that people may be skeptical but she wants to show how she helps those she feels are possessed

Powers: Rachel Stavis tells DailyMailTV that she has known since she was a child that she could sense the presence of demons and the reasons for them being there, leading to her being able to exorcise them - as she showed on actress Megan Duffy

Symbolism: Rachel Stavis uses a dagger as part of the exorcism, representing her casting out of the demon she says she has found in actress Megan Duffy

Stavis says Duffy has a 'Clive', the name she gives to low-level, low energy entities or demons that have caused the actress to feel negative and down in the dumps of late.

Stavis, dubbed the Sister of Darkness, has gone public with her extraordinary gift with the release of her new book: Sister of Darkness The Chronicles of a Modern Exorcist.

The horror screenwriter and novelist has secretly been an exorcist to the stars for years, helping Hollywood's elite to get rid of their demons.

She has cleansed thousands of tormented people from Hollywood moguls, actors and actresses to stay-at-home moms and politicians.

Stavis, 39, has never advertised her services and works pro bono, first starting her hobby by helping 'possessed' friends and family in her spare time.

But word soon spread around Hollywood about her unusual gift and now she has a waiting list of mostly high profile clients all desperate to be cleansed.

'My clients range all over the place, but I do see a lot of people you'd think of as famous,' she says.

'I see heads of studios, rock icons, Oscar winners, politicians, I see all kinds of people, I also see the girl next door and this grandma and regular people who are suffering as well.'

Most people's knowledge of the subject comes from watching hit 1973 supernatural horror film The Exorcist.

And Stavis says the movie, which sees a teenage girl possessed by a mysterious entity, isn't far from the truth.

'With The Exorcist, there's definite truth and the book is so amazing and it's one of my favorite books of all time,' she admits.

As a child raised in California Stavis quickly discovered she wasn't your typical girl.

She began to see 'monsters' floating around her bedroom or attached to other children.

'I realized very quickly I could see something other people couldn't,' she tells DailyMailTV in an exclusive interview.

'I tried to ignore it, I didn't feel like it was a gift at all, it was pretty scary and horrible.

Close to the truth: Stavis calls The Exorcist her favorite book and says the movie version is close to how she sees the world. The 1973 classic was adapted from William Peter Blatty's novel published two years before and saw Max von Sydow play Fr Lankester Merrin as he battled the demons who posessed Regan MacNeil, played by Linda Blair

understanding: 'With The Exorcist, there's definite truth,' Stavis tells DailyMailTV. She classified demons by the scale of their ambition and says that like The Exorcist portrays, demons attach themselves to people to 'feed'. 'They're gonna feed until they can't,' she says

'I learned pretty quickly that other people didn't have it because every time I tried to talk about it people were like, 'what, that's crazy, no, we don't talk about it'.

'So I didn't talk about it, I kept it hidden and went on with my life, became a writer and tried to live normally.'

But as she grew older a series of events in adulthood forced Stavis to acknowledge her unique ability and embrace her power to heal.

Since then, she has dedicated her life to helping others cast off the evil forces she says feed off of us.

'I see manifestations of entities, sometimes they have a face, sometimes they don't,' she explains.

'When I was a child I called them monsters...they still are monsters, these are things that have never existed as human beings.

'But there was no definitive guide book for me growing up so I had to create one.'

Stavis has named and classified all the demons she encounters from the most common and smallest of entities she calls 'Clives' - named because they look like drawings by artist Clive Barker - to the more dangerous 'wraiths' that she says cause night terrors and physical injury and 'roam-walkers' that can shift from person to person.

'I don't know if I can ever explain to people exactly how this works, how I can see things and how that translates,' Stavis says of her talent.

'I do my best to be down to earth, I'm definitely not new agey, out there, that's just not who I am, I'm not all peace and light.

'It is a weird juxtaposition of living, I'm a writer, I'm going through my life trying to have a sense of normalcy trying not to see these weird things, but you have to realize I've never not seen these things. If it all stopped one day that would freak me out, for me this is normal.'

Organized religions like the Catholic Church have a very specific set of guidelines about demonic possession and exorcisms, which the Vatican updated in 1999, but the subject has remained hugely controversial.

Afflicted: Megan Duffy turned to Rachel Stavis for a second time and allowed DailyMailTV to witness their encounter. 'It was really weird I just couldn't stop my teeth from chattering and I was shivering. It felt joyful. It was weird,' Duffy said

Cured? When Duffy opened her eyes she seemed drowsy and told DailyMailTV the experience - her second exorcism - felt 'strange'

Her view is that, like The Exorcist portrays, demons attach themselves to people to 'feed'.

'They're gonna feed until they can't,' she says. 'Most entities are looking to survive and this is what they survive on, low frequency energies they get from people. Who knows why anything exists the way it does.'

But the exorcist says the more 'malevolent' entities like the 'movie style' entities are looking for big targets, 'world changers'.

'Those types of entities are rare and they are looking for big game changers in the world,' she says. 'Not to be clichéd but this war between good and evil does go on, you see it every day. This is the type of entity is trying to tip the scales into darkness.'

Stavis' $1.2million house in the hills of Studio City, Los Angeles seems specially built for exorcisms.

The property has ornate stained glass windows, chunky medieval style doors and a Spirit Room filled with an eclectic collection of art and memorabilia.

But surprisingly Stavis hasn't lived in the house for years, in fact she only moved in two months ago.

In the Spirit Room actress Duffy is waiting patiently for her 'working'.

Stavis insists we all take off our shoes and no metal, jewelry, or cell phones are allowed.

The exorcist lights herbs and the air fills with an oily smoke that envelopes its occupants and after a while burns the throat.

Stavis closes her eyes and calls in her 'master teachers', before asking the 'higher beings' to enter the room.

Addressing them directly she said: 'I ask you to send your energy through the body and spirit, moving that energy through the body and spirit, identifying any negative entities that do not belong and do not serve and pushing them up and out.'

Half way through the 25 minute session Duffy seems overcome with emotion and suddenly lets out an almost surreal giggle.

Stavis walks slowly around Duffy shaking a rainstick and brandishing an ornate dagger against her wrist.

The whole thing is intense but there's no Hollywood drama.

No one throws up, the lights don't flicker, the doors don't slam and nothing falls off the walls.

Towards the end Stavis loudly chimes a bell over and over again, the chimes getting faster, until it suddenly stops. A Tibetan gong signals the end.

When Duffy opens her eyes she seems drowsy and said the experience - her second exorcism - felt 'strange'.

Tool of the trade: During the exorcism, Stavis shakes a rattle whose head is inspired by shamanic tradition. She says it and other noise makers agitate the energy in the room as part of the process of casting out the entities which have taken hold of the people who come to her

Spiritual: Rachel Stavis says she is agnostic but acknowledges the power of symbols from religious and spiritual traditions

Egyptian symbolism: Among the many spiritual symbols in Rachel Stavis' home in Studio City are those of the gods worshiped in ancient Egypt

'It was really weird I just couldn't stop my teeth from chattering and I was shivering. It felt joyful. It was weird,' she explained.

For Stavis exorcism can be exhausting.

'It's very draining, it's hard on the body believe it or not, you get aches and pains, there's been times after the more extreme exorcisms that I can't move for days afterwards,' she says.

ME AND MY EXORCISM Megan Duffy met Rachel Stavis at a bar for a mutual friend's birthday party and they started talking. 'At some point we went outside and I was a glass and half of wine in and she said, 'I don't want to alarm you but you have an entity that's attached itself to you and it's holding you back from the things you want to do'. 'At first I thought she was joking, it was a lot of friends who work in the horror film industry. But she told me more about what she did and offered to do a session with me. 'I was like, "is my head gonna spin, am I gonna puke green, what's going to happen?" 'I started becoming more intrigued and after about two years of becoming friends I said okay Rachel I'll take you up on it. 'At the time I had a lot of jobs that almost went my way but didn't which made me sad, I also had a couple of jerks I dated and some friends who were bringing me down and I didn't quite know how to fix it. So I thought why not and I thought it would be a cool being able to tell the story I had an exorcism.' Duffy, 38, who was raised a Roman Catholic, said the experience wasn't what she expected and she was initially 'scared' of what might happen. But after leaving Stavis' Spirit Room she felt amazing, so much so she decided to come back for a second session three months later. 'I started feeling there was a darkness trying to get hold of me again and I was fighting it,' she said. 'I believe the entity has now left me but there's always a chance it will come back.' Duffy added: 'I am a believer, absolutely, I guess who knows for sure whether it's a literal spirit or a placebo, I just know that what Rachel did made me feel whole and complete and empowered and strong and I started attracting the things I wanted in my life almost immediately, it worked.' Advertisement

A lot of Stavis' clients see her just once, however.

And she says for a lot of people coming to see her is the last resort.

'I've even had women come to see me who cannot conceive, they've tried everything and will call me a month later and say they're pregnant, people who have been addicted and have tried everything to quit who come once and never touch it [drugs] again, that's not a placebo, I can see that, they can feel that,' she says.

Stavis often sees clients who think they are possessed when they're not.

'If you're suffering with mental illness there's certainly a chance you could also have attachment, it's not mutually exclusive, but then there are people who think they're possessed when they're not,' she says.

As for her most extreme experiences she says they involve a specific type of entity which most people would consider the devil or the demon they see in movies like The Exorcist.

'I call it a movie style entity, I call it a 'roam-walker' in my book, because of the way it moves between the realms, if you will, is very easy, it is a very malevolent, very intelligent being.

'Those are the ones where the possession is very serious, you can see cuts and bruises on the body, it can move from person to person, which other entities cannot do.

'Those are the ones that are dangerous and scary. People don't realize that they can also take over buildings, which they do, they overtake spaces.

'When you are going through to exorcise the space and you have an entity essentially owning the space, that can be very dangerous, things can come off walls, things can fall on you. If you have people with you they can get sick, they can get harmed.

'There is another entity that takes over buildings as well, almost as malevolent as a roam walker, but not quite. That's called a Collector, what that does is it takes over a space where trauma has happened, where people have died in horrible ways.

'It collects the deceased people who have not moved on from that space in order to drain the living, to scare the living, if you will.'

Stavis recalls encountering a Collector in the basement of a former slaughterhouse in LA which is now used as a movie studio.

Movie bosses called her in after workers seemed to be getting hurt on set all the time, especially in the basement.

I've had skeptics come in who won't tell me anything about what's wrong with them and they come in expecting nothing, expecting BS, and those are the ones that sit up crying and say I don't know what just happened to me, I feel like a totally different human being now, and they leave joyous Rachel Stavis

Stavis says she went down to the basement in the middle of the night and water started dripping out of disused pipes.

In another room in the maze like 13,000 sq ft basement, utility cords that had been innocuous one minute were suddenly shaped like a noose the next.

Then she discovered something even more chilling.

'We went to another room and there was no pipes, no nothing, but the room was full of water, water was coming down the walls, we had to remove the entity.'

Stavis is aware that many skeptics don't believe in her 'gift' and she says being a woman and not religious doesn't help her cause.

'Naturally people are going to be skeptical about the whole thing, this is a very controversial subject, people feel very strongly, their opinions are very strong,' she says.

'But I've had skeptics come in who won't tell me anything about what's wrong with them and they come in expecting nothing, expecting BS, and those are the ones that sit up crying and say I don't know what just happened to me, I feel like a totally different human being now, and they leave joyous.'

However, convincing the doubters of her abilities isn't high on Stavis' agenda.

'We're afraid of these things, we don't want to change our world view, we don't want to look at this differently, because if this does exist in some way, that can be scary, but in a way too, that's also empowering.

'Once you know and understand it there are ways you can help yourself...so why not.

'You don't have to see things my way, you don't have to agree with it, but it's helping people. That's all that matters to me.'

As for any personal life Stavis says: 'I honestly don't have time for boyfriends I'm too busy and with what I do it is difficult.

'But at least now it's out there, they're gonna know going in, if somebody wants to ask me out, they're gonna be like "this chick is weird".'

Stavis admits that she's had several marriage proposals from people who have contacted her online, but doesn't intend to set up a Tinder profile any time soon.

She added: 'Being an exorcist has its downfalls but it's the most rewarding thing I do, because I believe it is my calling, why do I have this, there's a reason, there's a destiny involved.

'I don't charge people, this is not my job, I write, that's what I've done for years for a living, but I find this more rewarding in a lot of ways because I want to help people, that's what keeps me going.'

Sister of Darkness: Chronicles of a Modern Exorcist, by R.H. Stavis is available on Amazon.com.