Alfonso Cuarón’s Roma isn’t just his most personal film; it may be his masterpiece. An ode to his own childhood, growing up in Mexico City at a time of huge upheaval, the film marks his first on-screen return to his native country since 2001’s Y Tu Mamá También. And after last night’s rapturous world premiere at the Venice Film Festival, the film is firmly in the Golden Lion mix.

Off the back of his triumphant Best Director win for 2013’s Gravity — his last feature, replete with endless technological and filmmaking challenges — it wasn’t a surprise to learn Cuarón would go with something closer to home to follow up. But, he told me, the challenge was no less momentous.

Shot in black and white and drawn directly from Cuarón’s memories, the filmmaker didn’t just keep the screenplay from his actors (who found out what they were doing in each scene only as they did it), but from his creative team too. He would describe and detail set and costume choices, rather than allow for interpretation of what was written down. And he served as his own DP, after scheduling counted out his regular collaborator Emmanuel Lubezki, demanding that he be more present in every moment of the film than ever before.

Shortly after the film first screened, I sat with Cuarón to start to unpack this dense, beautiful film, which Netflix acquired for distribution, both theatrically and on their platform.

How close is this to your own story?

Ninety percent of the scenes that you see in the film come out of my memory. I’m not saying everything in this is linear, but what I did was compress around three years of memory into a narrative of 10 months. But almost every single scene is something I remember, complemented with the real-life Cleo [played in the film by Yalitza Aparicio]. I would talk to her about what she remembered.

And then there’s subtle elements of fiction because I wanted to include thematic elements that I found relevant both to character but also to this sort of broader story. What we tried to do is balance between character and a social context as well. Because we’re talking about personal scars. That is definitely a period that scarred me, probably for life. I can assume that it scarred the characters that play in the film. But also the social events that were portrayed are one of the most important and deep scars in the Mexican psyche. In the collective consciousness.

Is the real Cleo still alive?

Yes, she’s part of our family, or we’re part of her family, however that works.

Has she seen the film? How did she react?

Yes. She just cried. She kept on saying, “It was like this. It was like this.”

I found it more interesting when she went to the set, and I was very surprised because out of the blue I was doing the scene in which the mother is telling the kids that the father is going to stay for longer in Canada and they should do some drawings to ask him to come home. It’s also the scene where Cleo confesses to Sofía that she’s pregnant; and her only fear is that she’s going to be fired.

On that day, my mom and her arrived with my brother, and I was like, “Oh wow, the first day they come, they come for this scene!” I start shooting, I do a couple of scenes, and I go to check on them. I put up a tent with a monitor and headphones so they could watch and listen. And I see her crying and crying. I think, maybe it’s triggering very painful memories for her. I said, “Are you OK?” She says, “No, it’s just… poor little kids.” She was not even concerned about herself. She was concerned about the kids. She’s a beautiful soul.

You didn’t give anyone the script. You made this film as challenging as possible to shoot. Why?

Nobody had the script, and I shot in absolute continuity. That meant that I had talked to each of the actors about their character, about who they are. I talked to them about what they know, that not necessarily other people know. They had to keep it like this; they could not share that information with the other cast. I also talked to them about secrets they shared with one another. But they didn’t know the story, so every day they were playing out the story and learning their circumstances. And in that way, it was like life and it was playing with their own expectations.

Sometimes those expectations get fulfilled, sometimes it’s just boring and nothing happens. And sometimes everything goes against your expectations; that’s the unpredictable film.

Also, everybody you see in the film around the main characters, they’re real-life whatever they are. So we see real doctors and nurses. As we stage everything, I was just following their instructions, because they were the experts.

But, without wanting to give anything away, it was in so many organic moments that you realized this approach worked and paid off. There were many moments.

The movie opens with an airplane flying across the sky, reflected in a puddle of water. There are other planes throughout the movie. What’s the significance?

The thing is, because the film was, in so many ways, dealing with memory, but from my present, it had to do with my understanding of life today and my concerns; the thematic concerns that I have. A lot of that information is told more symbolically than overtly.

The planes work not so much in a thematic way, but for me they work in different ways. One is the transient situation. When they are there, things keep on going; there’s a universe that is broader than the life that [these characters] have.

On the other hand, they represent the constant presence of a modernity. A technological world that surrounds these characters and is in stark contrast to the shanty towns elsewhere. As humans, we have an amazing arc of technological development, but ethically we fluctuate.

The other, more metaphorical aspect of it is, this is a film that begins by looking at the ground. When the water comes in [in the first shot], you see the sky, but only as a reflection. And at the end, it finishes looking up at the sky. It’s that thing of the impossibility that there’s this metal object flying up there. It is the reflection of that impossibility that can happen when you try to come to terms with life.

There’s no straight answer for that, you know!