Bridget (Blake Lively), Carmen (America Ferrera), Lena (Alexis Bledel) and Tibby (Amber Tamblyn) are best friends living in Maryland. After many summers together, the four are finally going their separate ways for a few months: while Bridget heads to Mexico, and Lena visits family in Greece, Carmen and Tibby stay closer to home. No matter where they are, they are connected by a pair of jeans that they take turns sharing -- pants that fit all four girls and exemplify their tight bond.