In Melbourne, Australia, Hector and Aisha are hosting a big barbecue for their families and friends who come with several children. Hector’s somewhat controlling Greek parents appear too, bringing along too much food and their chronic disapproval of his non-Greek wife despite the two healthy grandkids and her success as a veterinarian. Aisha’s less-well-off friends, Rosie and Gary, arrive with their cherubic-looking son, Hugo, who at age three, is still breastfed and being raised according to a hippie parenting style that manages to be both sheltering and permissive. Hugo has a meltdown over a cricket game, which the older kids have let him join.  He raises a bat to strike another child, when Hector’s cousin, Harry, intervenes to protect his own son. Hugo kicks Harry who slaps him. Rosie and Gary call it child abuse and notify the police. 

The aftermath of the slap is told in several fulsome chapters, each devoted to a different individual’s perspective: among them, Hector, Aisha, Harry, Rosie, Hector’s father, and the teenaged babysitter Connie. Harry is rendered miserable by Rosie and Gary’s aggressive lawsuit against him. Connie believes she is in love with a philandering, substance-abusing Hector who in turn has unscrupulously led her on. Recognizing its alienation of her friends, Rosie sticks to her legal pursuit of Harry although she worries about the drain on their meagre finances, the exposure of Gary's drinking, and the anticipated criticism of their parenting style. Aisha is fed up with her husband’s edginess and submission to his parents, and she flirts with escape in the form of a handsome stranger at a conference.