It is 1967, and Larry Gopnik, a physics professor at a quiet Midwestern university, has just been informed by his wife Judith that she is leaving him. She has fallen in love with one of his more pompous acquaintances Sy Ableman.
For decades, next-door neighbors and former friends John and Max have feuded, trading insults and wicked pranks. When an attractive widow moves in nearby, their bad blood erupts into a high-stakes rivalry full of naughty jokes and adolescent hijinks.