Plot[]
In 1959, the peaceful, all-white neighborhood of Suburbicon is shaken up by the arrival of an African-American family, the Mayers.
Gardner Lodge, a mild-mannered man, is the father of a family in Suburbicon. One night, the home of the Lodge family is broken into by two robbers. The robbers tie the entire family up and kill the matriarch, Rose, with an overdose of chloroform. Her twin sister, Margaret, moves in to help take care of Nicky, the son of the family. Soon after her arrival, she begins to transform herself into Rose, dyeing her hair and having sex with Gardner.
As tensions mount between the residents of Suburbicon and their new African-American neighbors, charismatic insurance agent Bud Cooper arrives one day when Gardner is not home and begins asking Margaret questions, looking to clear up red flags in a life insurance claim made on Rose by Gardner shortly after her death. The conversation starts out innocuously enough, but Cooper grows suspicious when Margaret refers to herself and Gardner as a couple, after which Margaret kicks him out of the house.
Meanwhile, the two robbers who killed Rose are angry at Gardner after Nicky sneaks into the viewing room for a police lineup, where Gardner and Margaret denied that the two robbers were the ones who broke into their home. They are also mad that Gardner has not paid them a sum of money they were promised for killing Rose, and grow impatient when they are unable to reach him by phone. They make a plan to return to Gardner's house and kill Nicky and Margaret.
That night, as a prolonged protest at the home of the new African-American residents turns into a small-scale riot, Cooper returns to talk directly to Gardner. He tells Gardner that he knows the nature of his and Margaret's insurance fraud plan and attempts to blackmail them into giving him their entire payout in exchange for his silence. Margaret poisons his coffee with lye, and Gardner stabs him with a fireplace poker to finish him off. Gardner leaves to hide his body, trailed by one of the two robbers.
Margaret attempts to poison Nicky with a sandwich after he eavesdropped on her conversation with Cooper and contacted his Uncle Mitch for help. The increasingly suspicious Nicky does not eat the sandwich and, as Margaret is admitting defeat, one of the robbers strangles her to death before heading upstairs to deal with Nicky, who is saved by the arrival of Mitch. Mitch gives Nicky a gun and hides him in the closet before succumbing to a stab wound given to him by the now-dead robber.
On the way home from disposing of Cooper's body, Gardner is taunted by the other robber, who is suddenly killed by a fire truck. Arriving home, he finds the bodies of Margaret, Mitch, and the robber, and gets Nicky out of the closet. He offers Nicky a choice: go along with his plan to cash out an insurance claim and use the money to run away to Aruba, or be killed by Gardner.
The next morning, Gardner is dead, having eaten Margaret's poisoned sandwich during his conversation with Nicky. Nicky calmly goes outside to play ball with Andy, the son in the African-American family, as they are cleaning up the remnants of the previous night's riot.