Explores the emotionally and physically charged existences of three characters: Christina (Watts), Paul (Penn), and Jack (Del Toro). Initially not even acquainted, the trio and their destinies become irrevocably intertwined in a fusion of love, redemption, and obsession. 21 Grams is the weight we lose when we die, the weight carried by those who survive. 21 Grams: the gravity of life.