Forty-six year old Diane Després - "Die" - has been widowed for three years. Considered white trash by many, Die does whatever she needs, including strutting her body in front of male employers who will look, to make an honest living. That bread-winning ability is affected when she makes the decision to remove her only offspring, fifteen year old Steve Després, from her previously imposed institutionalization, one step below juvenile detention. She institutionalized him shortly following her husband's death due to Steve's attention deficit hyperactivity disorder (ADHD) and his violent outbursts. He was just kicked out of the latest in a long line of facilities for setting fire to the cafeteria, in turn injuring another boy. She made this decision to deinstitutionalize him as she didn't like the alternative, sending him into more restrictive juvenile detention from which he would probably never be rehabilitated. However, with this deinstitutionalization, she has to take care of him ...

"What does anyone want but to feel a little more free." Godspeed You! Black Emperor.

Mommy is a film about extraordinary, ordinary people. Individual scenes may be small and everyday, but what Mommy has to say is bigger, deeper: about life itself. The film reminded me of the above quote and freedom and our quest for it is the biggest thing Mommy has to talk about for me. It's about this and also about love and family and how those closest to us are so entwined they're not entirely separate beings to us. It's easily Dolan's most affecting work to date because within it every scene stems from and is full of emotion and conveys this to the audience.

In fact the film is so filled with emotion it is hard to remember the extremes it reached. It is so devastating by the end that I had to really think back to recall how I'd laughed out loud earlier on. There is a lot of humour in the film (in its observation of characters and what they say and do, but the time that got me most of all was when two characters laugh so hysterically you can't help but laughing out loud too – there's a real danger of us all descending into uncontrollable laughter alongside the ladies on screen!) which made me glad to watch it in a full cinema where the reaction could be heard from the audience. Despite this, by the end Dolan puts you through the wringer, and all that is left is our heartbreak for his characters and that that quest could never be.

Dolan's characters, for me are always his greatest strength. Not so much the specifics of them (though I must say these three are unforgettable in that sense!) but how they work. Since his first film, he has managed to express often deep or complex aspects about who his characters (and thus, who we all!) are inside in a way where I feel it. It isn't a thing that is easy to talk about because for me Dolan can tap into the kind of things the people in his films are and feel and do that often defy rational logic but yet which we all understand totally. Wow, confusing, much?

Anyway, here too, Die, Steve and Kyla (all exceptionally portrayed) are the heart of the film. They all feel like real people and despite the 2.5 hour running time, somehow at the end of the film you feel they've been snatched away from you. All actors can convey so much in an expression or action that you feel a world of their emotion and understand things about them without them needing to be said.

The three main characters in the film all become tied to each other in a way where they're kind of enmeshed. This is most true with Steve and Die who I feel are not entirely two separate people. They are Son and Mother, but more than this – they are man and wife, lovers, little kids – sister and brother, he's prince to her queen and Steve can be the father and Die the child. He is she and she is he and this is a bond that is wrapped up in who these people are. This makes the love Dolan's familial pairings have for each other unbreakable. Steve and Die fiercely are protective of each other: above all else. Yet in this, as in Dolan's other films, people entwined together struggle to exist almost as one being when despite how interwoven they are, they are individuals too. How to be separate, yet one? Dolan's characters push each other away and pull each other tight but they can never be entirely individual, nor can they escape each other. This is for me the true link between all of Dolan's films thus far.

I just want to say something briefly about the very start to illustrate the detail I felt in the film, without describing every detail which would sound trite. Though we'll come to know Die, Mommy of the title as many things, here we are first introduced to her as Mommy: she is shown in a visual sense as the roots, the trunk of the family tree.

I guess I should talk about the fact that the film is shot in a square of screen and to be honest I barely noticed it until a truly glorious moment when the screen opens up as a character exclaims their freedom and we see our three leads feeling free fleetingly. It gave me chills. After this moment, when the screen closes again – now you feel what at least I hadn't really noticed until then – that this aspect ratio works as a visual representation of how trapped these characters are. The screen closes in at a time that truly illustrates this and from then on the black sides feel as though they're kind of that-which-will-remain- forever-unreachable. The only time the screen expands again attests to this for it is a character's dream of the future.

Mommy is pitched in an ordinary world, but at extremes of emotion, but at the core there is always honesty in what it says and it's this that for me makes Dolan a great filmmaker. Dolan gets people and when you understand people enough to not just make a film in which you care about the characters, but to make a film where no matter the character, their experiences resonate: then, you have something magic.

"What does anyone want but to feel a little more free." I quoted at the start. Though Mommy wends through humour to ultimate heartbreak, for moments in it its characters are free and perhaps through this as we escape in its world, it allows us to feel a little more free also?