21 Grams is supposed to be how much weight a body loses when it dies. It's a great title and premise for a movie, but this complex, non-linear film isn't really about that. It's about death, dying, mistakes, despair, sorrow in a totally non-linear moral universe. The lives of three people converge in very harsh ways. One man kills another in a hit and run, the dead man's heart is transplanted into the third man's, and that man gets involved with the dead man's wife.
Sean Penn is even more brilliant in this film than Mystic River. Naomi Watts is the new Meryl Street. Benicio Del Toro is consistently a sure bet for every role he plays.
But this is a confusing movie and not so easy to watch.