Oh Brother! I Slept with My Stepsibling!

A sheltered, low-income teenager breaks her strict routine for the first time at a prep school party, where drinking leads to a night with a stranger. Her search for her missing mother and stepfather takes a tragic turn when the couple dies in a car accident. Left feeling guilty, she moves in with her stepfather's wealthy former wife, a cold and manipulative woman, and soon discovers that the stranger from that night is actually her stepbrother.