The IMDB trivia page claims that Clint Eastwood maintains that this will be the last movie he acts in. Sob! Say it ain't so, Clint!
[Update: as I type, February 2018, he's been the lead actor in two more flicks, and had an uncredited role in one more. Not prolific, but… Hopefully, he's immortal.]
Clint plays Walt Kowalski, a crusty retired autoworker living in a decaying Detroit neighborhood. Things aren't going well: (1) His wife has just died; (2) And (worse) before she died, she forced the local priest to ask Walt to make confession; (3) His curmudgeonly hardass ways have estranged him from his family; (4) A Hmong family has moved in next door, and Walt sees them as "gooks", much like the ones who he fought in Korea; (5) Gangs of various ethnicities prowl the streets; (6) His health is deteriorating; (7) One of the Hmongs, the teenage boy Thao, tries to swipe Walt's prize possession, a gleaming 1972 Ford Gran Torino.
But on the other hand, his dog likes him.
Unsurprisingly, underneath the irascible bigoted exterior is a man of bravery and character. Walt develops a relationship with the Hmong family, and tries to save Thao from dead-end gang membership.
As I type, IMDB users rate Gran Torino #81 on their Top 250 movies of all time. I don't know about that, but it is pretty good. As I pointed out at the time it got pretty much snubbed by the Oscars, yet another data point in favor of the view that the Oscars are increasingly useless.