We Were Liars (Part I)

Usually, I would give you a quick summary of what the book is about, but I don't really know myself. All the author gave was:

A beautiful and distinguished family.
A private island.
A brilliant, damaged girl; a passionate, political boy.
A group of four friends-the Liars-whose friendship
turns destructive.
A revolution. An accident. A secret.
Lies upon lies.
True love.
The truth.

Although it's vague, the author left enough to leave me intrigued and wanting to read this book. I've currently only read 68 pages. The main character is named Cadence (Cady) who's a teenage girl. Her friends are Gat (her love interest), Johnny, and Mirren. One day, she went swimming at a beach alone. I guess she must have swam too far, and there were huge rocks, and her head slammed onto it. After the accident, she doesn't remember how it happened. But something that changed was Gat didn't really talk to her anymore. Before, they were both involved with each other and they even confessed how they loved one another. What changed? I don't know, but hopefully, and probably, I will find out as I keep reading.