The new screenplay from the author of the hugely acclaimed Amores Perros is another masterpiece: structurally complex and profound.Cristina (Naomi Watts) is a recovered drug addict, happily married to an architect, with two beautiful children. Paul (Sean Penn) is a mathematician with a critical heart ailment, trapped in a spent relationship. Jack (Benicio Del Toro) is an ex-convict desperately trying to keep himself pure. Three souls in isolation from one another, until a terrible incident enmeshes them together . . .The title of 21 Grams alludes to a mysterious loss of weight in the human body at time of death. Guillermo Arriaga's bold and brilliant screenplay (filmed by Amores Perros director Alejandro Gonzalez Inarritu) moves freely through time, before and after the fatal moment when these three lives collided.The screenplay is accompanied by exclusive interviews with the film-makers about the making of 21 Grams.