Is this the most screwed up Shion Sono film? While watching it I was convinced that it surely had to be, but now I'm thinking again. Bearing in mind that the competition includes Noriko's Dinner Table, I'm not sure that it's even the most screwed up Shion Sono film of 2005. Suicide Club is more gross and Noriko's Dinner Table for me more shocking because it's more controlled and realistic, but Strange Circus is an extraordinary piece of Grand Guignol that does nothing to reassure you about Sono's mental health.

What's different about this one is the sex. There's a bit of gore, including a chainsaw, but it's basically all about the sex. I hope you're getting scared already. Please bear in mind that Sono is a proper filmmaker, so he'll have come up with a serious story with characters you want to watch. This isn't schlock. It contains appalling abuse, yes, but it avoids showing us the worst stuff (i.e. the scenes that would get the film banned and Sono lynched) and it's just as interested in the psychological effects years later that this abuse has had on the survivors.

Just as importantly, it doesn't leer at its nudity. There are naked women, yes, but you never get the impression that they're doing it to give you a stiffy. On the contrary, this film is surreal and arty even by Sono's standards, with nudity simply being part of the story he's telling.

The first thing we see is the Strange Circus itself, in which the ringmaster invites members of the audience to get their heads cut off with a guillotine. A twelve-year-old girl volunteers. In a voice-over, she tells us that she thinks she was born on an execution stand, or else that she was standing in on one for her mother. Firstly we see her witnessing her parents having sex. This isn't good, but it's not scary yet either. In a scene shortly afterwards, we see her at school being summoned to the office of the headmaster, who also happens to be her father. He's playing a film as she comes in. This scene is deeply wrong and from here on I'm going to stop going into detail about the plot, partly for reasons of taste.

We have incest. We have self-mutilation. We have a family that becomes broken and unhinged in ways that wouldn't even have occurred to me, with the little girl's brain being warped into new shapes and her mother faring even worse. We have a back-and-forth timeline that shows us what will have happened to the characters years later, combined with unreliable narration and outright fantasy. The corridor outside Daddy's office at school is sometimes blood-red from floor to ceiling, for instance. It's as if someone's slaughtered a whale there. The Strange Circus itself would appear to be fantasy as well, although you never know. It's going way too far by any standards, yet Sono's story is sufficiently freaky and twisted that despite all this it's surprisingly watchable. The story's all about the women. Daddy is a monster, yes, but he's also so weak and thin that we don't even really hate him. Obviously he deserves everything he gets (which is a lot), but the film's opinion of him is that there's nothing really there. He's uninteresting, whereas I'd never seen anything like the psychological journeys of his wife and daughter.

There's a development at the end, of course. I misread it at first and thought I was seeing something grotesque and appalling, but I'd underestimated Sono and in fact was seeing something else, also grotesque and appalling. There was a point in the finale where I thought things were getting a bit overblown, even by this film's standards, but then Sono pulled it back and found enough emotional weight to make it matter again.

The most noteworthy thing about the cast is the choice of lead actress, Masumi Miyazaki. For more than a decade she was an actress and nude model who appeared in the Japanese edition of Playboy, but in 1996 she married and gave up show business. She became a housewife and lecturer, living in America. However ten years after her last film Shion Sono somehow lured her back for Strange Circus, although ironically in November of the same year she announced she had breast cancer. She's good. She looks great for her age, but more importantly she successfully takes us on this deeply bizarre emotional journey. It's a proper acting performance, not just the camera gawping at some gravure idol.

The little girl's good as well, crucially. The other important cast member isn't Dad, but a sleazy editor played by Tomorowo Taguchi, who's a regular in Takashi Miike and Shinya Tsukamoto films (most notably Tetsuo and Tetsuo II) and who has also worked as a director, narrator, cult musician, illustrator, writer and pornographic cartoonist.

It should probably be emphasised that Shion Sono isn't incapable of making gentle, meditative films. Be Sure to Share (2009) sounds as if it matches that description, for instance. He's also done the odd experimental documentary, so it's not as if he's a one-trick pony or anything. However in the West, he's probably always going be best known for intense, disturbing films like this. Technically it's ero-guro, but we're at the classy end of the spectrum. In fact this film is artistic enough that one of its imdb user reviews is from a child abusee engaging with it as a proper movie, although she disagrees with Sono's take on the psychological effects of abuse. I'd have been terrified if she hadn't, actually.

This isn't a film for everyone. Even leaving aside the people whose brains it would explode, it's an arty, sometimes surreal piece with a story in which a lot of the action is internal. Er, I've just spotted the double meaning in that. Personally though I think it's far watchable than you'd expect of this kind of thing, with scary character development and some real surprises. It won a Reader Jury prize at the Berlin International Film Festival, by the way.