Annie (Kristen Wiig), is a maid of honor whose life unravels as she leads her best friend, Lillian (Maya Rudolph), and a group of colorful bridesmaids (Rose Byrne, Melissa McCarthy, Wendi McLendon-Covey and Ellie Kemper) on a wild ride down the road to matrimony. Annie's life is a mess. But when she finds out her lifetime best friend is engaged, she simply must serve as Lillian's maid of honor. Though lovelorn and broke, Annie bluffs her way through the expensive and bizarre rituals. With one chance to get it perfect, she'll show Lillian and her bridesmaids just how far you'll go for someone you love.

When Abigail and Parker return from New York City to visit their home town, they discover that their best friend Rachel is a bridesmaid in the wedding of their childhood friend, Caitlyn, and Tony, who was Rachel's boyfriend until Caitlyn interfered. Abigail and Parker decide to run some interference of their own. They manipulate Caitlyn and become bridesmaids as well so that they and Rachel can sabotage the wedding from the inside. With help from a police detective who happens to be a groomsman, the girls strive to ruin Caitlyn's wedding while dodging her controlling mother and hopefully reuniting Tony and Rachel.