It’s hard to imagine that anyone who sees 21 Grams won’t be absolutely blown away. An unforgettable treatment of mourning and melancholia, the film is devastatingly powerful with exceptionally raw performances from Sean Penn, Benicio Del Toro and Naomi Watts. Even more dazzling is the film’s remarkable non-linear structure, but as director Alejandro Gonzalez Inarritu and writer Guillermo Arriaga’s follow-up to the multifarious Amores Perros, it’s probably no less than we would have expected. Though formally very bold, Arriaga, the man behind the method, never worried unduly that the film’s anti-chronology would descend into chaos.

“I don’t think people are hard-wired for one kind of storytelling,” he explained on his recent visit to the Dublin International Film Festival, “and I think that every different story has its own way of being told. It’s also the way stories are told all the time. As we are sitting here, how many topics have we covered, but we jump around from one thing to the other because that’s how people speak and communicate. My only worry about the structure was that people would be unable to follow the story on an emotional level because of the gaps in storytelling, but people do fill in those gaps themselves. They make their own movie.”
As a William Faulkner buff – like all people of discernment – Arriaga didn’t have to look far for inspiration. “My two great loves are Faulkner and Shakespeare,” says the acclaimed writer. “I love that Faulkner can match form and content so perfectly, but something else gave me the idea. I was in Washington attending a film festival where Amores Perros was being shown over the course of three nights, and I noticed that the questions being asked by the audience at the end of each screening were really very strange.
“At first I just thought it was a Washington thing, but a Mexican came up one evening and told me that the film he had just watched was very different to the one he had seen at home. So I went along and discovered that the reels had been all jumbled up, and that’s the way they were been shown. And I thought that was interesting that even with huge narrative gaps that the audience could follow the film. So that’s what I did with the 21 Grams screenplay.”
The film, which deals with the destructive aspects of grief, also had antecedents in the aftermath of a tragic accident witnessed by Arriaga.
“I always say that my inspiration comes from the streets and the fields of Mexico City, where I have been living all my life. Some years ago, I was driving home late for my own birthday party, where my wife and friends were waiting, when I came to an accident where a man was lying dead. Someone had run him over. Beside him was a photo of a woman with a little girl in her lap. And I thought, this man is dead but his family are waiting for him at home, so I joined that with the idea of my birthday party for the plot.”
The movie title refers to the weight a person loses at the exact moment of dying, although Arriaga points out that this is not a universally corroborated medical fact, but “a metaphor for a weight that you may have to carry always”. Indeed, it’s this aspect of the film that makes it emotionally compelling, for 21 Grams is an incisive anatomy of pain and the way it can diminish people until they’re little better than a ghost in their own life. “That the very heart of the film,” he says. “At one point Naomi Watts says that she has become like an amputee, that she’s cut off from everything and everyone and paralysed by grief. The dead can exert an enormous influence after they are alive. They can be powerful in their absence. The living can also become so overshadowed by pain, that they can only inhabit the world in a ghostly way.”

21 Grams is released March 5