Emma Allan and Olivia "Liv" Lerner are best friends who have planned every detail of their weddings, since first witnessing a wedding 20 years ago at the Plaza Hotel. They both have made it a priority to be married in the same location in June. In the present, while hanging out at Liv's place they find a Tiffany box hidden in the closet. Both friends are excited knowing that Liv will soon get a proposal from her boyfriend. That same night Emma's boyfriend proposes to her. Liv gets restless waiting for her boyfriend to pop the question and eventually confronts him. He replies he was planning on doing it that night but then asks her on the spot. Both girls start planning and are expected to be each other's maid of honor. They schedule a meeting with New York's most famous wedding planner, Marion St. Claire, who tells them there are three spots open in the plaza. Two on the same day and one a few weeks later. They each chose a different day but due to a clerical error they are scheduled to have a wedding on the same day, June 6 (three and a half months later).