從一個人墜樓的不可思議事件開始，校內人心惶惶、困惑的監護人、校方想息事寧人、吵鬧的媒體和SNS，潛在的欺凌、妒忌、偽善、惡意問題捲起了巨大風暴，究竟是誰在說真話，誰在說謊，一群學生渴望知道真相，決定在學校開庭公審，自己學校真相自己尋…。原作是以1990年代的公立中學為舞臺的，電視劇版則換成了SNS普及的現代私立高中。

从一个人坠楼的不可思议事件开始，校内人心惶惶、困惑的监护人、校方的息事宁人、吵闹的媒体和SNS。潜在的欺凌、妒忌、伪善、恶意问题捲起了巨大风暴，究竟是谁在说真话，谁在说谎，一群学生渴望知道真相，决定在学校开庭公审，寻找真相。

On Christmas morning, Fujino Ryoko finds her classmate Kashiwagi Takuya’s dead body at their snow covered school. The police and the school conclude that Kashiwagi Takuya died by suicide. At that time, an anonymous letter is delivered to Fujino Ryoko. The letter states that Kashiwagi Takuya was murdered by a group of students including Ooide Shunji. The media and SNS begin to question whether Kashiwagi Takuya really died by suicide or was he murdered. The school principal tries to take control of the narrative, but this leads to a more chaotic situation.

Fujino Ryoko is disturbed by people's reaction to Kashiwagi Takuya’s death. She asks for a trial and an unprecedented school trial begins.

クリスマスの朝、雪の積もった校庭で藤野涼子（上白石萌歌）はクラスメイト・柏木卓也（野村裕基）の死体を発見する。警察や高校が自殺と断定する中、涼子のもとに“同級生・大出俊次（坂東龍汰）らによる殺人”を告発する匿名の手紙が届く。自殺か他殺か、転落死をめぐって騒ぎだすマスコミやＳＮＳユーザー。校長の津崎正男（小林薫）は事態の収束を図るも、さらなる事故が起きてしまう。

次々に起こる不可解な出来事。大人たちの対応に納得できない涼子は謎の他校生、神原和彦（宮沢氷魚）とともに立ち上がる。「裁判をしませんか。わたしたちで」。前代未聞の学校内裁判が始まる。

도쿄의 평온한 서민가에 위치한 조토 제3중학교. 크리스마스 날 아침, 눈 쌓인 교정에서 2학년 남학생 가시와기 다쿠야가 시신으로 발견된다.

경찰은 옥상에서 뛰어내려 자살한 것으로 결론을 내리지만, 곧 그가 교내 불량학생들에게 살해당했다는 내용의 고발장이 관계자들에게 날아든다. 이 사태는 학교폭력이 얽힌 끔찍한 살인사건으로 발전하고, 매스컴의 취재가 시작되면서 일파만파로 커져 가는데….