Alexander Cooper, an 11-year-old boy, experiences a series of unfortunate events beginning with gum in his hair and continuing with more mishaps at school, all while feeling neglected by his family. As he shares his woes, his upbeat parents and seemingly perfect siblings offer little sympathy, leading Alexander to make a birthday wish that they all experience a day as terrible as his. The next morning, the rest of the family starts to encounter their own spiraling string of misfortunes.

Alexander's father, Ben, faces critical workplace challenges while attempting to impress a potential employer. His mother, Kelly, confronts crises at her publishing job. Brother Anthony's disastrous preparations for prom and sister Emily's stage debut fraught with setbacks add to the chaos. As the day progresses, the Coopers find their patience and resilience tested, ultimately learning the importance of sticking together as a family through even the worst of times.