I believe I read this young adult fiction as part of English class back in middle school or early high school, likely around 2005. Notably it introduced me to the Lazarus effect, where a person who has died spontaneously returns to life.

To the best of my memory, the story follows a boy and his sister who become trapped in a theater when a fire breaks out on the balcony. Falling debris kills the sister and the boy, who escapes, describes her with lifeless eyes. They later recover the sister who awoke, soiled, and trapped in debris. She is reluctant to talk about her experience and later reveals this is because death is utter nothingness and not the light at the end of the tunnel she had been taught.