Following the self-set rule 'Time destroys everything', we are taken through a harrowing, gruesome night in the the lives of Alex, Marcus and Pierre, played in episodic reverse order.
Time heals all wounds,' goes the old phrase. 'Time destroys everything,' counters an on-screen caption in Irreversible. But this is by no means an exercise in shock-value nihilism or gratuitous violence against women: two-thirds of the running time takes place after the controversial rape scene. Noe's intention is to mourn the beautiful thing that has been destroyed, not to glorify its destruction.
That's why his bold narrative structure - telling a rape-and-revenge story backwards - isn't a cinematic gimmick. He is literally undoing a crime to make a profound social and artistic statement about evolution.
As in 2001: A Space Odyssey, the film progresses from an animalistic orgy of violence to an embryo's serene spirituality; here, from a noisy nightclub hell to a peaceful outdoor heaven. Its self-conscious structure and unflinching portrayal of rape and murder are designed to make us think and feel at the same time. That's not a definition of entertainment, but it is a definition of meaningful, provocative art.
Distressing, certainly, but also genuinely thought provoking and to that end, important.