imdb), is a fine example for this.
The film shows just 2 married couples who are talking about a conflict their sons had before on a schoolyard, costing one of the boys 2 teeth. "Carnage", which is based on a theater play by Yasmina Reza (wikipedia), is very spartan; you see just 4 actors staying in a single room.
But anyway, I had a lot of fun watching the flick. I enjoyed spotting how the characters tried to settle the conflict in the beginning, but got more and more agitated and how the situation escalated in the run of the movie. Both couples were middle class, but on the opposite sites of the spectrum. There was a growing dynamic between the couples and also between the married spouses, reflecting conflicts of social status, education, income, sex, Weltanschauung, whatever. These conflicts lead to dialogues which were sharp and sometimes funny.
"Carnage" benefitted of course from the superb actors: The parents of the injured boy and hosts of this event were played by Jodie Foster, as a very political correct but unemployed book writer and collector of art books, and John C. Reilly as her husband and proud owner of an appliance store. Their counterparts were represented by Kate Winslet, as a slick investment banker, and Christoph Waltz, playing an extremely busy and self-conscious attorney.
My favorite was Waltz. I was fascinated how the Austrian actor`s character couldn´t care less about all the fuss and indulged his own ignorance. I want to see more from Waltz. I also enjoyed spotting Kate Winslett loosing her coolness and Jodie Foster getting more intense as her liberal conviction got more and more cornered while the earth bound John C. Reilly tried to be a rock in all the turbulence.
Bravo Herr Waltz! Bravo Mrs. Winslett & Foster! Bravo Mr. Reilly!