In Boston, Ally Darling is a thirty-something woman who is struggling to make better decisions with her life. Her boyfriend Rick breaks up with her when she asks him to attend her sister Daisy's upcoming wedding, and she then gets laid off from her job. While taking the subway home, Ally comes across a ''Marie Claire'' magazine article entitled "What's Your Number?", which says that women who have more than twenty lovers in their lifetime have difficulty finding a husband. After making a list of all the men she slept with, she realizes that her number is nineteen, making her decide not to have sex with anyone else until she finds "the one". This lasts all of a few hours when she wakes up after Daisy's bachelorette party and discovers that she's hooked up with her ex-boss Roger whilst intoxicated.