In the novel Sia by Josh Grayson, the main character Sia Holloway is seventeen years old on the day she wakes on a park bench with no memory of how she got there or her previous life. While her first instinct is to reach out to a police officer for help, she hesitates. She has a feeling that there is some reason she doesn’t want to return home. When night falls on her first day alone, Sia is befriended by a homeless woman named Carol who helps her learn how to navigate the perils of the streets, how to find food, and how to look out for other homeless people. The friendship blossoms, and Carol urges Sia to seek help finding her family. Sia remains against the idea.

After about a week, Sia and Carol have fallen into a routine. Sia is waiting for food at a local soup kitchen when one of the volunteers confronts her. The young man shouts at Sia, telling her she has no right to be here. Fearful, Sia rushes from the building and is struck by a cab. She wakes in the hospital to find that her name is Sia Holloway and that she is the only child of a wealthy couple. Her father is in films and her mother a former model. Still without memories, Sia is taken home where she struggles to equate herself with the incredible home, lavish life, and closet filled with designer clothes. She pushes herself to return to school, hoping as the doctor predicted that a normal routine might jog her memories. But, she soon realizes that her so-called friends are cruel and ruthless and that Sia had been the leader of this group prior to her amnesia.

Sia also comes to realize that her idyllic home life isn’t what it seems to be. Her mother is an alcoholic. Her father’s film studio is struggling to the point of collapse. As Sia begins to interact with the family’s housekeeper, she realizes that she’s played no role in helping her family succeed. Armed with a determination to help rather than harm, she encourages her mother into rehab, spends time with her father, and volunteers her help gathering donations for the victims of an earthquake. As she makes changes in her own life, those around her watch to see whether Sia will revert once her memories return.

She breaks up with her perfect boyfriend, drops out of the cheer leading squad, begins to make new friends, and distances herself from the cruel crowd she’d so eagerly led before her amnesia. As her relationship with one particular boy named Kyle gains ground, Sia wants to follow her heart. However, Kyle refuses, fearing that Sia will return to her previous lifestyle once her memory returns. Along the way, Sia changes the lives of others as she leads by example.

While Sia is helping distribute water and candy bars to those impacted by the earthquake, a little girl’s impulsive hug opens the gates, allowing all of Sia’s memories to return. She finds herself more determined than ever to live a life with which she can be happy. A screen writer turns Sia’s story into a movie script which saves the family from bankruptcy. With her share of the movie’s take, Sia and Kyle open a soup kitchen run by Carol. Each prepares for a happy life.