Like Mystic River–with which it shares far more than just a stunning, sorrow-wracked performance from Sean Penn–21 Grams uses raw emotional power to explore the aftermath of violence, the way a single wrongful act can ricochet through the lives of everyone it touches. The accomplished second feature by Amores Perros director Alejandro González Iñárritu, 21 Grams focuses on the life-changing consequences of a fatal automobile accident that kills Naomi Watts' husband and children. After an extended period of sobriety, the grief-sodden Watts starts abusing drugs again. She also becomes attracted to Penn, the terminally ill beneficiary of her late husband's heart transplant, and a man entering the bleak final stages of his life and his failing marriage. Benicio Del Toro co-stars as an ex-con father and husband whose garish tattoos are only the most physical manifestation of a hard life filled with violence, drugs, and prison. After decades spent in and out of jail, Del Toro has found religion and turned his life around, but when he fatally wounds Watts' family with a truck advertising his love of Jesus, his hard-won faith is irrevocably damaged. In 21 Grams, Watts, Del Toro, and Penn all occupy a horrific limbo somewhere between life and death. Tragedy has robbed them of their ability to enjoy life, but it's also spared them, at least temporarily, the finality and certainty of death. Working once again with ace cinematographer Rodrigo Prieto and screenwriter Guillermo Arriaga, Iñárritu sustains a mournful atmosphere throughout 21 Grams, creating a world where the absence of the dead is felt as strongly as the presence of the living. A nearly unparalleled actor's showcase, the film boasts performances of impressive quality and quantity: Penn brings a coiled, Brando-esque intensity to a performance that eerily echoes his turn in Mystic River, but he's equaled by the formidable Del Toro and Watts, who tear into their own meaty, challenging roles. Their complexity matches the film's. At a time when the justice system seems intent on extracting an eye for an eye, 21 Grams suggests that the harshest punishment may be the one enacted by the consciences of the guilty.