Lynne Ramsay: 'With fantasy, you can sleep at night. This terrifies people more'

How do you film shocking bestseller 'We Need to Talk About Kevin'? It wasn't easy, director Lynne Ramsay tells Jonathan Romney and reveals the story behind some of the pivotal scenes

Making yourself scarce is one way to enhance your reputation as a film-maker.

It worked for Terrence Malick, and in Britain it's worked for Lynne Ramsay. Not that Glasgow-born Ramsay, 41, would have chosen to be so elusive, but her new film We Need to Talk About Kevin has been hailed as a triumphant return for a director too long lost in action. Ramsay debuted with the acclaimed Ratcatcher (1999), followed by Morvern Callar in 2002, then spent four years planning an abortive adaptation of The Lovely Bones – only to find Alice Sebold's book becoming a bestseller and the project spiralling out of control (it was eventually filmed by Peter Jackson).

We Need to Talk About Kevin saw Ramsay getting back on track the hard way, with a gruelling 30-day shoot in Connecticut. The film is adapted from Lionel Shriver's novel about a woman, Eva (Tilda Swinton), whose unusually difficult son Kevin grows up to perpetrate a high school massacre. (John C Reilly plays Eva's husband, Franklin, and Kevin is played as a toddler by Rock Duer, as a boy by Jasper Newell and as an adolescent by Ezra Miller.)

But Ramsay stresses that her film isn't about a Colombine-style slaughter. "The high school killings are, for want of a better word, a smokescreen for what's really going on." The real subject, she says, is the mother-son relationship, and Eva's agonisingly equivocal feelings towards her boy.

Ramsay says she recognised parallels in families she knew: "Older mothers, friends of mine who don't feel totally at ease with a baby, not feeling that instinctive connect that you're meant to feel. There have been films like Rosemary's Baby and The Omen, but they're fantasy, so you can sleep at night. This terrifies people more."

After her enforced absence, Ramsay plans to stay busy behind the camera: she has several feature ideas, and she may also make an Olympics short about wild swimming – depending how the weather holds up this autumn.

Kevin, she says, "was almost a military operation – it'd be nice to do something more free form, as a palate- cleanser".

We Need to Talk About Kevin is released on Friday

Five Key Scenes: The view from the director's chair

1. Eva sees red at a tomato festival

"I was looking for a very visceral opening that felt euphoric but also dangerous – that takes Eva back to her days before Kevin, but also has this element of threat or dream. It was like, 'How do I get across that she travels, but in a way that has other psychological meanings as well?'. The tomatina festival happens in Buñol, in Spain – it started because they had a glut of tomatoes. We went out there with a documentary-sized crew, and it was quite a risky thing to shoot – this was 40,000 people in a tiny street. You can see it's completely mental. I don't know if any other actress would have done that, it was sort of dangerous. Me and the cameraman got slammed against the wall. I got tomatoes all over me. It was touch and go; we had 15 minutes, and Tilda [Swinton] dived in. It stank – it was urine and booze, testosterone. I had to literally shove people out of the way. I thought, 'Something bad's going to happen here,' but Tilda was so up for it."

2. Eva and the teenage Kevin square off

"That's a real restaurant: it looks like a set, but it's not. All those places round there [in Connecticut] look like sets. This was a really interesting scene to shoot – Tilda and Ezra [Miller] had worked up to it by then. We shot chronologically as much as possible, and they hated each other at this point. Even when you see the two of them together in the first photographs, there's a dislike – it's partly their characters. It wasn't that they weren't getting on, but Ezra had studied Jasper (Newell, Kevin aged seven) and taken on his movements, so there was a creepiness, an awkwardness. I always liked the fact that Eva and Kevin mirrored each other slightly. I wanted him to look like her, and her to see that monster within herself. It's that moment every parent recognises with teenagers – she says, 'How's school going?' and he says, 'Do you want a course schedule?' He takes her to task – 'Don't give me the mummy-son conversation now'. I've seen that kind of thing between mother and son, but he takes it to an extreme. They were kind of mirroring each other, they were watching each other, getting into the whole thing. It totally was a face-off, it was real 'Fuck you' from him."

3. Eva and Franklin – 'a real couple'

"John [C Reilly] phoned me up because he wanted to work with me. I think he'd made a list of directors he wanted to work with, so that was quite an honour. John and Tilda got on really well: both their kids are in Steiner schools, they have a lot of similarities – and his kids were actually doing archery lessons, like Kevin in the film, because he didn't want them to use guns. John would come round every night during the shoot and I'd make him dinner – it was a good chill-out after intense days. He was very in awe of Tilda – very: 'She's a goddess!' I think he found her really attractive; there was a vibe. I wanted a more real couple. That's what I like about Don't Look Now – you've got Julie Christie, who's really gorgeous, and Donald Sutherland, who's a bit runny-nosed. John added a bit of humour – I loved working with him."

4. Kevin and the nappy

"Rocky Duer (Kevin as a toddler) was amazing, but he did have a freak-out when we were doing this scene – he said, 'I'm much too big to be wearing a nappy.' Luckily, Ezra was there for the whole shoot because he wanted to study Jasper and Rocky and their mannerisms. He saved the day – he took Rocky outside and got Santa Claus to call him or something, and he stopped crying. We didn't have a lot of time to shoot – and when you're working with kids and you only have 10 minutes .... Rocky is very small, he looks bigger in the picture than he is. Directing a three-and-a-half-year-old is quite hard. He came in, climbed on the chair. I said, 'Can you say "Mommy"?' He said (sulky voice), 'No.' But he did exactly what I said – then got up and walked out of the room, completely silent. He took direction like I've never seen. This is the rolling-the-ball scene (where little Kevin refuses to co-operate with his mother). I couldn't believe I was getting that – it was like CGI or something."

5. The McMansions of Connecticut

"We shot the film in Connecticut. All those McMansions there, they're like sets inside – it's a real location but it looks like a set. Everything's a façade within Eva's family, and those places do look kind of cold. When I think about American films by Europeans, I think of Wim Wenders – Paris,Texas Americana. But actually it's a super-bland place – especially if you're outside the big cities and you drive from one mall to another. The houses are 'mock', big, rich houses, but there's something slightly tacky about them. Connecticut is a hugely rich area, and a beautiful area, but I wanted the feeling that Eva is the boho one in the couple, so ending up in the 'burbs like that was like death for her. It might seem cartoonish in the film, but it was surprising how much it was really like that."