In 1975, magistrate Pierre Michel (Dujardin) is tasked with bringing down the Marseille mob "La French", whose French Connection links drug suppliers in North Africa with buyers in America. Working with the DEA, Pierre targets the kingpin Zampa (Lellouche), who has managed to remain untouchable. Over the next six years, Pierre works with partner Jose (Gouix) to target Zampa's cohorts, discovering in the process that swathes of the police are in on the crime ring. And Pierre's wife Jacqueline (Sallette) is terrified that his life is at risk.

Director-cowriter Jimenez keeps the film's pace brisk, with a driving sense of narrative that focusses on Pierre's tireless quest for justice. Even when he tries to take time off, Pierre keeps getting dragged back into the messy array of thugs that make up La French. But there are so many of them that getting to the core of the operation seems hopeless. This is kind of how we feel watching the movie, even though Jimenez skilfully makes it clear who is good, bad or corrupt.

Dujardin has terrific presence in the central role, with a heroic tenacity and pragmatic working style. His big emotional moments carry a real punch, as they reveal layers beneath the tough-judge exterior. And when he dives into the fray of action, Dujardin cleverly makes it clear that Pierre is far out of his depth. Opposite him, Lellouche is just as complex and intriguing, a family man who runs a successful multinational corporation that just happens to be illegal.

Thankfully, this kind of subtext is subtle. Jimenez takes care to introduce each of the characters as fully formed people, with good and bad shadings, which makes every scene crackle with possibilities. There may be far too many characters and plot wrinkles to make clear sense, which can feel exhausting in a film this long. But the bigger picture is gripping, and a couple of shocking moments carry a real wallop.

When Laura (Le Besco) dies, she leaves behind an infant daughter, grieving widower David (Duris) and devastated pal Claire (Demoustier). As her husband Gilles (Personnaz) tries to support her, Claire eventually she feels up to helping David with the baby. But when she drops by she's shocked to find David dressed in Laura's clothes, complete with wig and make-up. Oddly, this actually brings them closer as friends, as Claire takes "Virginia" out shopping. The question is whether something else is going on here, and where the lines of attraction are drawn between male and female.

Ozon has a great time blurring those lines, as each scene is packed with innuendo, both in the dialog and in subtle visual cues. David, Claire and Gilles all clearly have fluid sexualities, and yet they also have a strong sense of where their love and loyalty lie. Duris, Demoustier and Personnaz all deliver remarkably layered performances that hint constantly that whatever we're thinking is probably wrong. It's a seriously clever portrait of the complexities of human sexuality, and the film wisely refuses to lock them into any boxes.

Duris delivers an especially gorgeous performance, shifting brilliantly from David to Virginia and back, as glimpses of the other one linger here and there. This character is a stunning bundle of masculinity and femininity, all while maintaining David's straight sexuality. His chemistry with the terrific Demoustier is amazing, because she is clearly more attracted to Virginia than to David. And Personnaz gets to add his own far-from-simple yearnings into the mix. So where this is heading is impossible to predict.

Everything is orchestrated with a sure hand, from Ozon and the actors to Philippe Rombi's lush score and Pascal Marti's sleek cinematography. And Ozon also drops in continual Hitchcockian touches (including references to most Hitchcock classics), adding to both the wrenching emotions and a hint of growing suspense. The clever epilog might annoy mainstream audiences who like their movies to come with easy answers and simple-to-define characters. But the complexity is the ultimate point: life is full of variety, don't crush it.

• TOP 10 FILM

In Kiev, teen Sergey (Fesenko) moves into a new school for the deaf, immediately being hazed by the student leader King (Osadchiy) and given a job as a petty thief when the kids turn into criminals after classes end. Rising through the ranks, Sergey is assigned to accompany Anya and Sveta (Novikova and Babiy), driven by the woodworking teacher (Panivan), in their work as prostitutes at the local truck stop. But when Sergey falls for Anya, buying her time with his pocket money, he crosses a line and has to be punished.

Cinematographer Valentyn Vasyanovych films these scenes in long takes that are sometimes fixed and at other times elaborately choreographed to capture a pungent sense of the grubby settings. Several scenes are simply jaw-dropping, including a private abortion and a nighttime assault, shot in single takes that both boost the emotions and dazzle the eye. Some of these sequences feel a bit stagey, but the novice actors are remarkable at creating vivid characters using only their physicality.

There isn't a spoken word in the entire film, but there's plenty of ambient noise. And the actors add remarkable layers to these young people, with spiky interaction as the story accelerates through the rather long running time. Encounters become increasingly urgent, with moments of joy and fear, satisfaction and frustration, all played both through facial expressions and full-bodied movement. Most amazing is how easy it is to identify with Sergey and Anya, the two most deeply defined characters.

It's also fascinating that a film with such an essentially simple plot can engage the attention so powerfully over two hours. It helps that first-time feature filmmaker Slaboshpitsky continually undermines the nastiness with black humour, including a stunningly staged accidental death. Meanwhile, the explicit scenes of sexuality and brutality are so carefully orchestrated that they feel more like artistic depictions than voyeuristic excesses. And in the end, the movie leaves us deeply shaken. We admire it, but we might hesitate to recommend it to our more sensitive friends.

Axel, Ana and Jonathan (Delgado, Almeida and Prociuk) are locked away in hiding as the world falls apart outside. The neighbours have turned into zombies that need to be shot, and they're making a video diary to document the experience. They also play board games, and Jonathan is giving Axel an all-over tattoo. But both Axel and Jonathan are going crazy because it's against the rules to have a relationship with Ana, and things turn even more intense when they capture a zombie (Lagre) and bring him home to play with.

The movie has a terrific sense of the hot, fly-infested city these three young people seem so alone in. Filmmaker Behl is essentially just documenting the details of their life, as pretty much all they have to do is kill time and occasionally venture out to find supplies and to clean up their neighbourhood. Much of their interaction is inexplicable, although we understand their rules and private jokes the more time we spend with them. We also see more of the tensions between them, including jealousies and secrets.

Performances are cleverly understated, with flickers of humour here and there, plus lots of unspoken feelings. Annoyingly, many scenes are shot in near pitch-blackness, which makes them very difficult to see. But there are moments that are genuinely involving, as well as scenes that build a creeping sense of suspicion and dread. And as the strain between these three young people grows, their situation becomes increasingly unbearable.

The video diary motif awkwardly takes over the film, as they break the rules to watch each others' tapes. And Behl reveals virtually nothing of the streets outside their locked-down house. When a survivor arrives at the door, they chase them off. But things inside are so messy, as they struggle to control their feelings for each other and their darker, more primal instincts begin to take over. Meanwhile, the plot itself moves so slowly and obliquely that it's not easy to care. Although we can certainly understand their desire for peace. Whatever the cost.