Carmen, Tibby, Lena and Bridget have been best friends all their lives. They live in the same small American town and usually spend every moment of their long summer holidays together. Tibby buys a pair of jeans in a second-hand shop and the girls discover that the trousers fit each of them perfectly, despite their different figures and heights.
Summer is always a special time for the four teenage best friends: Bee, Tibby, Carmen and Lena. This year there's an added poignancy as the girls know this is their last summer together. Can the strength of their friendship overpower the feuds in their families and leave the girls with happy memories of the third summer of the sisterhood?
Lena's in love - but will it end in a broken heart? Bridget's about to face up to some painful truths about her late mother; Carmen's hoping destiny will play her cards right, and Tibby's going to film school. The Travelling Pants and the sisterhood that wears them are back for their 16th summer.
Ama, desperate to live up to her family's expectations, finds herself on an outdoor adventure summer camp. Tomboy, loner Polly discovers that her grandmother used to be a model and decides she's going to follow in her footsteps. Jo's parents' are still grieving the death of her older brother and she's stuck in the middle of their messy divorce.