Seventeen-year-old Alex seriously messes up during her senior year at an Orange County, California high school, skipping classes and staying out all night at Hollywood night clubs with older guys, in an effort to distract herself from some unpleasant realities.

Instead of a fresh start, high school provides more grief and isolation to Echo, whose older sister died a year earlier, but insights gained from Zoe's diary--a fifteenth birthday gift from Zoe's boyfriend--about her sister's life and death change Echo in ways she could have never expected.