Redacted, 15

War as not seen on 'News at Ten': Based on real events, this study of Iraq and how it is portrayed is fuelled by rage

Brian De Palma is a director famous for his fascination with the mechanics and ethics of image-making, concerns that he has tended to spin into elaborate, exuberantly lurid mainstream thrillers. In Redacted, however, he's not out to entertain: De Palma is on a mission, and on a small budget ($5m). "Redacting" is a term used by the military for editing or censoring. The title refers to the way that, De Palma argues, the public has been denied real images of what's happening in Iraq. This is his attempt to put the record straight.

A fiction based on real events, Redacted focuses on an act of rape and murder by US soldiers in Iraq. Two privates stationed long-term in Samarra – frustrated, stir-crazy and violently embittered – rape a 15-year-old Iraqi girl and burn down her family's home. The incident is recorded by one of their comrades, Private Angel Salazar (Izzy Diaz), as part of a video diary that he sees as his sure-fire passport to film school. He's not participating in his buddies' acts, he's convinced – just filming them, so that the truth can be told.

Apart from the crime itself, De Palma is interested in the ways in which the reporting of war is affected by the processes of making and transmitting images. De Palma presents his HD-shot film as a collage of found materials. One strand is Salazar's gauche, self-congratulatory video; another is an apocryphal French documentary, factually informative but portentously larded with Handel and, for all its earnest intentions, ripe with phoney filmic rhetoric. TV news is represented by an embedded Arab reporter pointing her microphone at GIs in the thick of a dubious search mission. What gives Redacted its present-tense immediacy is the use of internet images, including an Iraqi militant website, a tearful posting from a soldier's wife, and a furious rant by a punkish teenager in the US (by all accounts, a verbatim transcript of a genuine diatribe) denouncing American arrogance abroad: "Sieg Heil, motherfucker!"

That teenager's reference to the My Lai massacre signals that De Palma is asking whether anything has changed since Vietnam. Real-life inspiration notwithstanding, Redacted is something of an update of De Palma's 1989 Vietnam drama Casualties of War, which focused on a similar shocking incident. While that film's urgency was mitigated by its Hollywood polish, the jigsaw quality of Redacted, signalling its hot-off-the-press intentions, makes this a much rawer and more confrontational work.

But Redacted is not as sophisticated a study of image-making as De Palma might wish. Its analysis of the morally compromised nature of documentary-making is actually less acute than that of George Romero's latest zombie chiller Diary of the Dead: it's often the case that genre films, with their covert attention to contemporary issues, manage to cut deeper than polemically direct statements. In Redacted we learn: that brute force in the US army runs unchecked; that unschooled recruits are likely to react violently to intolerable conditions; and that the military system tends to silence or crush those with moral qualms. But there's little critical perspective beyond the anger.

For all its apparent cinematic complexity, and despite its strong unknown cast, the film often feels awkwardly theatrical. Embodying positions rather than character, the cynical, self-justifying brutishness of the two main perpetrators (Patrick Carroll, Daniel Stewart Sherman) isn't entirely believable. Or, I might have thought so if I hadn't seen Errol Morris's forthcoming documentary Standard Operating Procedure, in which Lynndie England, who participated in the Abu Ghraib atrocities, chirps away about having no regrets, with all the witless complacency of a Jerry Springer guest.

De Palma ends with a montage announced as comprising real photos (in fact, all but two are real): they depict unspeakable mutilations inflicted on Iraqi adults and children. The images are all the more dreadful in that faces have been blacked out: a "redaction" inflicted by the film's producer, against De Palma's wishes. This bitter irony might have made the montage even more telling, if only De Palma hadn't plastered it with a tear-jerking swathe of Tosca, a horribly intrusive mis-step.

Redacted is a valid alternative to those well-meaning films, such as In The Valley Of Elah, that ultimately grieve for the American people's latest on-screen loss of innocence. It is ungainly and insistent – flawed, but fuelled by a rage that's hard to ignore.

Need to know

Brian De Palma put Robert De Niro in the spotlight with his 1968 film 'Greetings'.

He is regarded as the heir to Hitchcock for his thrillers 'Obsession', 'Blow-Out', 'Body Double' and 'Dressed To Kill', though the latter saw him accused of misogyny. He revived Hollywood's gangster tradition with 'Scarface' and the 1920s crime saga 'The Untouchables', in which De Niro reportedly wore the underwear of the real-life Al Capone. De Palma is now working on its sequel.