Twenty-two years after their first body-swapping adventure, Tess (Jamie Lee Curtis) and Anna (Lindsay Lohan) find themselves navigating new family dynamics. Anna, now a mother to teenage daughter Harper (Julia Butters), is engaged to Eric (Manny Jacinto), who has a daughter of his own, Lily (Sophia Hammons). As the two families prepare to merge, tensions rise between the soon-to-be stepsisters.