Eloise McGarry, having been unceremoniously dumped by the best man via text, reluctantly decides to attend her oldest friend's wedding. She finds herself seated at Table 19, a spot designated for the guests who were expected to decline. Alongside Eloise are an eclectic group of misfits: Jerry and Bina Kepp, a middle-aged couple struggling with their marriage; Renzo Eckberg, an awkward teenager desperate for romance; Jo Flanagan, an ex-nanny with a hidden agenda; and Walter Thimble, an enigmatic ex-con with a troubled past. Initially strangers bound only by their lowly status at the wedding, they begin to bond over their shared awkwardness and personal predicaments.

As the day progresses, Eloise and her fellow Table 19 outcasts navigate a series of embarrassing mishaps, revealing conversations, and unexpected revelations. Despite initially feeling like outliers, they start to uncover each other's hidden depths and vulnerabilities, forming a supportive network. The group's interactions oscillate between humor and poignancy as they re-evaluate their past decisions and current lives. Through the course of the wedding festivities, bonds are tested, secrets are exposed, and each member is presented with an opportunity for personal growth and redemption.