Hallie (Lindsay Lohan) is growing up in Napa Valley with her vineyard-owner father, Nick Parker (Dennis Quaid). Annie (also Lindsay Lohan) is raised in fashionable London by her mother, Elizabeth James (Natasha Richardson), a renowned wedding gown designer.

Unaware of each other’s existence, fate intervenes when the girls coincidentally meet at summer camp in Maine. Eager to meet their respective parents, the girls devise a scheme to switch places and ultimately, reunite their mom and dad. Their plan takes on urgent proportions when they learn their father has fallen for the young, beautiful and opportunistic Meredith Blake (Elaine Hendrix).