The main character is Matt Fowler, who is grieving the murder of his son, Frank. Frank was killed by Richard Strout because Frank was dating Strout's estranged wife. Strout shot Frank in front of the wife and children.
Matt's wife, Ruth, is struggling with the death of her son. She is also struggling at the perceived lack of justice, as Strout's family is wealthy and he seems to be "getting off" for the murder. To help his wife cope, Matt conspires with his friend, Willis, to kill Strout. They abduct Strout, making it look like he jumped bail, and kill and bury him in the middle of the woods, miles from town. The story ends with Matt telling Ruth that is it finished, and that they will let their other children think that he ran away.
The story is told in episodes, not in a chronological sequence. This type of structuring for the plot allows the audience to get emotionally invested in the story, and allows for foreshadowing and irony. The point of view is 3rd person limited, because we see several different character's experiences, but don't know all their thoughts and feelings. Matt's thoughts and feelings are the focus of the story, and we understand him to be the protagonist. The story is set in New York in August, though we aren't given a particular year.
Different themes emerge from this story, but a key theme seems to be violence and responsibility. Specifically, Dubus seems to want his audience to consider different reasons behind violence, and ethically whether they are justifiable. In Killings, Matt seems to feel his violence against Strout to more justifiable than Strout's violence against Frank. Furthermore, the connotation of the title itself invites ambiguity -- why "Killings" rather than "Murders," a more precise description of the type of violence seen? This complex issues invite the audience to ponder and discuss the role of violence in our culture.