We Were Liars by e.Lockart

Cady's family enjoys idyllic summers on a private island each summer. She has a crush on Gat, a family friend, who joins them at Beechwood each summer. The four of them, Mirren, Johnny, Gat, and Cady are the Liars. Sitting atop Cuddledown's roof, one of the summer houses, Cady feels invincible.

The four of us Liars, we have always been. We always will be.

No matter what happens as we go to college, grow old, build lives

for ourselves; no matter if Gat and I are together or not. No matter where we go, we will always be able to line up on the roof of Cuddledown and gaze at the sea. The island is our. Here, in some way, we are young forever.

A horrible accident, though, during summer 15, leaves Cady critically injured. She was found on the beach with a head injury and hazy memories. Will Cady's memories of summer 15 ever return?

During summer 17, Cady turns her room into an incident room, meticulously recording what she remembers on graph paper and post-it notes above her bed. She is still in love with Gat but something pivotal has happened that has changed their relationship.

Gat, the only non-Sinclair in the group, is the one who first opens Cady's eyes to social issues. Not every family, he says, owns a private island. He is of Indian descent, like his Uncle Ed, who has developed a relationship with Cady's Aunt Carrie. 

Lockhart skillfully interweaves fairy tales in the novel that foreshadows  the surprising twist in Cady's story. Gat, the outsider, is the mouse in many of these fairy tales.

Gradually, readers learn that Harris, Cady's Grandfather, has tried to manipulate his daugthers and grandchildren. Though he's not a bad man, not crooked, he is entitled and reckless with his money. He is prejudiced against Ed and Gat; he pretends to accept them when he actually cannot abide them.

Gat is the first to caution Cady that Harris does not want the two of them to date. The Aunts begins fighting over belongings. Cady, whose motto is to do what she she most fears, undertakes a daring plan to rectify their idyll.