we were liars by E. Lockhart

If you're looking for a book with a major plot twist that will leave you quite possibly in tears, read this book. Lockhart writes the story of a girl named Cadence Sinclair, who comes from a privileged family. Every summer they all go to an island together, but one summer there is an accident and she loses some of her memory. You are swept up into the journey as Cadence tries to find out exactly what happened around the time of the accident. She makes the decision to spend another summer with Gat, Johnny, Mirren and "the Littles" on the island, hoping to find answers to her questions....and she does. But they weren't the answers she thought she would find.
This book may seem a little slow at first, but trust me, once Cadence starts putting pieces together, you won't be able to put it down.