Wesley Doyle (POWERS BOOTHE) is the FBI agent who's been working on the "God's Hand" serial murder cases that have been occurring in Texas. When a stranger (MATTHEW McCONAUGHEY) suddenly appears in his office one night and says that he knows the identity of the killer, the seasoned agent knows things are never that easy, but is nevertheless intrigued.
The man, who claims to be Fenton Meeks, states that the killer was his brother, Adam, who recently killed himself. Figuring he has to investigate such a claim, Doyle cuffs the man and they go for a drive in the direction of the Rose Garden where the victims' bodies are supposedly buried.
Along the way, the man recounts the story of his childhood that led up to this point. It seems that 12-year-old Fenton Meiks (MATT O'LEARY) and his 9-year-old brother, Adam (JEREMY SUMPTER), lived a relatively happy life with their single dad (BILL PAXTON). That is, until the father had a vision one night of an angel who informed him that God had chosen him to kill "demons" walking among them posing as humans.
While Adam believes his father, even when he starts to kill people on a "list" supposedly given to him by the angel, Fenton can't believe what's occurring. Even so, with no other family members to tell and nowhere to go, the boy feels trapped by what he sees as rampant insanity that's infected his dad and brother. As the man continues with his story of what happened then during his father's murder spree, he and Agent Doyle get closer to their destination and some surprising revelations.