The structure will most likely turn off moviegoers within its few minutes and in the direction of a different, less competent filmmaker this structure can easily fail.  Many comparisons will be made to the non-linear structures of Pulp Fiction or to the directors previous film, Amores Perros, but those films eventually follow through a linear narrative structure through a majority of the film.  21 Grams is almost unrelentless in its hop, skips, jumps and leaps forward and backward, then all over again, with its storytelling.  This is a strong testament to Inarritu's confidence in his directing and his editor, Stephen Mirrione (possible oscar nominee?).

SPOILERS AHEAD

At the beginning of the film we are immediately shown our trio of characters already thrust into each other's lives and then in the shift of a scene they are days from the incident that will bring their lives crashing together.  It's this jump in time that makes us start asking questions.  When is this?  When did we last see this scene?  Where does it belong?  What precedes it?  What follows it?  I found myself wondering where one of the characters was at in reference to the scene onscreen that they do not appear in.  While Paul was meeting Christina (Naomi Watts) for the first time, where was Jack (Benicio Del Toro) in reference to the previous scenes he was in.  Each scene unravels a bit more of information from not only the past, but the future as well.  What keeps a person willing to put this puzzle together is the compassion and care you place on a certain character or all three.  You find yourself wanting to know how their stories connect and where does it really start and end for each of them.

Naomi Watts (The Ring, Mulholland Drive) plays Christina, a happily married woman with two daughters and on a successful drug-free rehabilitation.  All is drastically turned upside down for her when her family is unexpectedly killed in a hit and run and she resorts to drug use as her only source of escape.

Sean Penn (Mystic River, I Am Sam) gives a great performance as a terminally ill man, Paul, agonizing over his potential last few days.  In the beginning of the story, he is in a hospital, about a month from dying, but that doesn't keep him from taking a quick smoke out of the sight from his loving and caring girlfriend, Mary (played by Charlotte Gainsbourg).  Mary is desperately attempting to have a child with Paul before he dies and prove her love to him, although she feels he doesn't love her.  In fact, Paul does not love her and once he receives a heart transplant and becomes healthier again, he pushes Mary away and becomes determined to find out information about his donor.  His interests in doing so seem more of an intuitive purpose, because once he finds out who the heart he received came from and the way it came to be available, he makes an instant connection towards Christina.

Benicio Del Toro (Traffic, The Usual Suspects) marvelously plays Jack, a born again family man who is trying to stay on the path to salvation.  His past however casts over him in a guilt-ridden shadow.  In his youth he was constantly in and out of jail for numerous crimes.  Now, with a wife and two kids, he has found religion and puts a great deal of effort into his faith.  In Jack's face you see all the guilt and burden of his past built up.  Happiness itself would be a sin for him and in his heart he had much to suffer before he can experience any joy.  Little does he know that he will be the cause of much misery, even if it is accidental.  No matter how desperately Jack holds on to his faith, this accident is the greatest challenge to it he has endured.

21 Grams, although some would consider it to have a pretentious or intricate storytelling style, is actually a very technically bare and simple film that is carried through by the directing and acting.  The sound design is minimal and the film itself appears to be shot on 16mm, giving it a bleak and dark tone.

At one point in the film Christina is talking with her father during the funeral of her family about her feelings towards the death of her mother when she was younger.  She couldn't understand how her father could ever laugh again or be able to manage without his wife.  He simply tells her life goes on.  For these three characters, each one has managed to get in the right path for a better life, Christina has her family and stopped her drug use, Jack found a life without crime and Paul received a heart for a second chance at life.  However, these "life goes on moments" are prove that at any given time, you'll be faced with another setback, another test of one's character and endurance.  As in Amores Perros, Alejandro Gonzalez Inarritu binds characters through a car incident that sets off a discourse in their lives, many times as they are on the brink of success or fulfillment, only to have it taken away from them and left to endure a greater obstacle.

Alexander Rojas doesn't sit in the aisle seats..