Many years after Tess (Jamie Lee Curtis) and Anna (Lindsay Lohan) endured an identity crisis by switching bodies, Anna now has a daughter of her own, Harper (Julia Butters), and is engaged to be married to Eric (Manny Jacinto), who has a daughter of his own, Lily (Sophie).

However, Harper and Lily despise each other. As the four women navigate the myriad challenges that come when two families merge, Tess and Anna discover that lightning might indeed strike twice — after they all pay a fateful visit to a fortune teller.