When Yoon Do-Joon, a mentally challenged teenager, is arrested for the horrible murder of a girl his mother does not believe it. She will stop at nothing to prove that her baby boy did not do this and that the cops and the community are framing him and taking advantage of his disability. The cops are well-meaning but are ready to close the case since he “confessed”. The lawyer is a slime ball who advises her to take the plea deal. We follow Mother as she starts her own investigation complete with evidence collection, interviewing witnesses, deputizing one of her son’s friends and not giving a crap about anything other than getting her kid out of jail. The performance of Kim in the role of Mother (the film does not even give her a name…she is just mother) is fantastic. She goes all over the place. She can be tender, devious, loving, doting and even violent. This is ultimately about two people who are so dependent on each other that they cannot tolerate the idea of separating. When a crime, society and the law threatens this order they will fight back.