Detective David Mills (Brad Pitt)’s Timeline and Summary

Mills shows up for his first day on his new job in the big city and immediately annoys his partner, Somerset.
After sending Mills away from the crime scene, that of a man who seems to have eaten himself to death, Somerset recommends that Mills be put on a different case.
When a lawyer ends up killed, Mills investigates that crime scene instead, even though it seems to be an even more high-profile case.
Somerset discovers the murders are linked by the seven deadly sins, so he encourages Mills to research them and look for more links.
Mills' wife, Tracy, invites Somerset over for dinner, and they have a nice time.
After the meal, the detectives have to work, and they eventually find another clue—fingerprints behind a painting.
The fingerprints lead them to the next victim, a man tied up and starved for a year.
When they go to the apartment of another suspect, the man opens fire on them and Mills give chase.
Mills injures himself in pursuit and gets whacked over the head by the killer. The killer has the opportunity to shoot Mills but doesn't.
After two more murders, the killer turns himself in. But, it's not the end.
He leads them into the desert, saying the last two victims are there.
But they're not. Yet. A deliveryman shows up with a package. It has Mills' wife's head in it.
Doe reveals that he killed Tracy, Mills' pregnant wife.
Somerset tries to get Mills to walk away, but Mills doesn't. Mills shoots Doe about seven times and is arrested.