From the time John J. Macreedy steps off the train in Black Rock, he feels a chill from the local residents. The town is only a speck on the map and few if any strangers ever come to the place. Macreedy himself is tight-lipped about the purpose of his trip and he finds that the hotel refuses him a room, the local garage refuses to rent him a car and the sheriff is a useless drunkard. It's apparent that the locals have something to hide but when he finally tells them that he is there to speak to a Japanese-American farmer named Kamoko, he touches a nerve so sensitive that he will spend the next 24 hours fighting for his life.

A.C.O.D. follows a seemingly well-adjusted Adult Child of Divorce (Adam Scott) who is forced to revisit the chaos of his parents' (Catherine O'Hara and Richard Jenkins) bitter divorce all over again after his younger brother (Clark Duke) decides to get married.

Carl, a fisherman in the waters off Washington state, has been found dead, drowned in his own nets, but with a serious head wound. Was he murdered? Post-war anti-Japanese sentiments are still running high, and a murder suspect is found in the local Japanese-American community in the form of Kabuo, another fisherman, who had a grudge against Carl's family. Ishmael, the small town's newspaperman, may have the information that would acquit Kabuo, but can he ever put his jilted love for Hatsue (Kazuo's wife) aside?