Mother (2009)

In a small South Korean town, a devoted mother lives quietly with her only son, a young man with an intellectual disability. But when a high school girl is brutally murdered, the son is accused of the crime. As the town turns against him and the police build their case, the mother embarks on a relentless quest to prove his innocence. In her desperate search for the truth, she'll show the lengths a mother will go to protect her child.