It's the fallout from Becca calling off her wedding to Sean. Her parents are angry, Sean is heartbroken, and her new self-appointed position as VP of Simon's company isn't all it was cracked up to be.
Becca, as she nears 40, is about to embark on her second wedding to Andy Kelly, but her joy is tempered by the absence of her old best friend Lolly who's a no-show, having dropped out of their relationship years ago. As Becca mulls over her past with Lolly and the mishap of her marriage to her first husband, Sean, she wakes up on her wedding day and discovers that it's 15 years in the past - she's about to marry Sean, her own parents are still married, and Lolly is still in her life. Becca must now decide to either go ahead with her marriage to Sean and watch the years play out as they have before, or chuck it all and try for a re-do of the history of her life that's still in the future.