Red (2008)

The titular colour is the name of a 14-year-old dog, the loving sole companion of a golden age widower by the name of Avery (Brian Cox). Avery is a good man whose life has been wrought with personal catastrophe. As the film opens, he and Red go out to a lake for an afternoon of fishing. A trio of young delinquents happen across them, and decide to get their kicks by robbing the old man. Avery doesn't put up a fight, and openly offers up all the money in his wallet—20 dollars. Out of pure, unprovoked meanness, one of the kids shoots Red dead. Avery is shattered.

He tracks the kids down and goes directly to the shooter's home, looking for a simple apology. The cleancut hooligan denies everything and his wealthy and influential father not only backs him up, but makes sure that the law will be on his side. With the death of Red, Avery has lost the last living thing that mattered in his world. He fills the emptiness with boiling obsession, following the thugs around town, forcing confrontations, until all involved are pushed onto a path of desperate, uncontrollable violence.