Widowed for a long time, a mother lives alone with her only son, Do-joon. He is 28 years old, a shy and quiet young man. In the aftermath of a terrible murder, the woman’s hopeless, helpless son becomes the prime suspect. There is no real evidence against him, but the police throw groundless suspicion at him simply because there is no way he can prove his innocence. Eager to close the case, the police are happy with their cursory investigation and arrest the boy. His defense attorney turns out to be incompetent and unreliable, making a conviction seem inevitable. Faced with no other choice, his mother gets involved, determined to prove her son’s innocence.