For a moment it's as if they've never been apart. They're still Vixen and Cassandra, summer sisters forever. The rest is a mistake, a crazy joke.'

Vix Leonard is twelve when she meets dazzling, reckless Caitlin Somers. Invited to spend holidays on Martha's Vineyard with Caitlin and her eccentric, mysterious family, Vix is welcomed into a life totally unlike her own. As days of bold adventure give way to nights of shy discovery, she and Caitlin come together in the complications of growing up; the refuge of belonging; the pact to Never Be Ordinary . . . Until one devastating summer when a local boy changes everything.

Years later life has driven them apart, but the bruise of their friendship remains. When Caitlin begs Vix to return to the Vineyard for her wedding, Vix knows she will go. She wants to understand what happened that last shattering summer - and why her best friend still has the power to break her heart.