在法院擔任公設辯護人的李慧貞,接任一樁由名律師王國超中途解除委任的青少年殺人案。 因來自法院系統的背景得不到被告阿成的信任,再加上現有證據都對阿成不利,而審判長石法官更是打算在退休前俐落解決這起案件;眼看法庭的審理過程都只是形式,阿成重罪難逃。但阿嬤阿鸞始終相信自己的孫子阿成即使涉案也不會是主使者,於是百般求情奔波。 有一個兒子的慧貞被阿鸞感動,決定求助前刑警竣良的協助抽絲剝繭,重新了解案情真相。 但在所有人證、物證、法官心證都不在己方的有利立場,慧貞將如何面對與扳回劣勢。Li Hui-zhen, who is a public defense counsel at a court, takes over a murder case involving teenagers of Ah-cheng. But the existing evidence is unfavorable to defendant. Seeing that the courtroom procedures are merely formalities, it seems as if Ah-cheng will certainly be found guilty. With the grandmother frantically seeking leniency, Hui-zhen is moved and decides to seek help from former criminal policeman. However, with everyone's testimony, the material evidence, and the judge's opinion going against her, how can Hui-zhen deal with and reverse her weak position?