*In the summer of 1977, when shy and quiet Victoria Leonard is in 6th grade, Caitlin Somers, moved to "Vix's" school from Aspen.
*Vix was stunned when Caitlin asked her to go away with her that summer to her father's summer house Martha's Vineyard.
*Vix had a hard time convincing her strict parents to let her go. Her mother, Tawny thought the rich were different and that Vix shouldn't try to fit in, but her father, Ed convinces her mother to allow her to go. Her family became jealous of her that she could escape in the summer; except for Nathan who had muscular dystrophy and was extremely close with Vix.
*Vix and Caitlin become "Summer Sisters", and best friends. They share secrets about love, life, and growing up in the house at the Vineyard. "Double Trouble", as they are known on the island, share numerous adventures.
They meet "National Treasure", two older college guys, one of whom Vix falls in love with, they baby-sit for famous television stars, and vowed to each other never to be ordinary (NBO). Lamb, Caitlin's father, and Abby, his wife, give Vix a scholarship so she can go to a private school with Caitlin.
*The Chicago Boys, Abby's son and his friend come to stay at the house on the Vineyard and "Double Trouble" are a constant tease to them. Vix continues to go with Caitlin for every summer until they are 17, when Vix leaves angry and confused after a fight with Caitlin.
*Vix still returned to the island for a few summers after that but did not stay with Caitlin. She stayed on Trish, and old friend of Lamb's sailboat. She continued her relationship with Bru, a "National Treasure" and worked to save up for college money.