The story is set in a small town where there was a sensational "campus defense case" that caused a nationwide sensation. Ten years ago, high school student Lin Feng stabbed Li Hao, a classmate who bullied him, with a knife because he was bullied by his classmates on campus, causing Li Hao to be seriously injured and unconscious. Lin Feng was sentenced to ten years in prison, while Li Hao has been in a vegetative state. The case sparked controversy and discussion over the "legitimate defense" law.
Ten years later, Lin Feng was released from prison and returned to the lively town. He hopes to rebuild his life, but finds himself still discriminated against and ostracized. His only friend is his lawyer, Wang Xiaochen, who was once Lin Feng's high school classmate and the only one defending him. Wang Xiaochen is now a successful lawyer, and he is full of sympathy and guilt for Lin Feng, hoping to help him reintegrate into society.
At the same time, Li Hao's sister Li Xue also returned to the town. She is a journalist who decides to re-investigate a case from ten years ago in order to find out the truth. She suspected that Lin Feng was not the real murderer, but a scapegoat who was framed. She began to contact Lin Feng and developed feelings with him. But what she didn't know was that her actions attracted the attention of another person - that is, Su Ming, the prosecutor who was in charge of the case that year. Su Ming, who has now been promoted to deputy prosecutor general of the city prosecutor's office, is uneasy about Li Xue's contact with Lin Feng, fearing that they will reveal the secrets he had covered up.
The story gradually unfolds with the investigation of Li Xue and Lin Feng, and they discover that there is a shocking conspiracy hidden behind the case. It turned out that Li Hao was not an innocent victim, but a cruel bully. He once raped a girl and caused her to commit suicide by becoming pregnant, and this girl was Su Ming's daughter. In order to take revenge on Li Hao, Su Ming used Lin Feng as a scapegoat and made him bear the charge of attempted murder. And Su Ming himself secretly arranged for someone to go to the hospital to cut off Li Hao's oxygen tube, making him a vegetative person.
These shocking truths shocked Li Xue and Lin Feng, and they decided to take Su Ming to court to expose his crimes. However, they face great pressure and resistance, because Su Ming is not only a senior prosecutor, but also has a strong background and power. He did not hesitate to use all means, including threats, bribes, framing, assassinations, etc., to stop Li Xue and Lin Feng's actions.
The story finally reaches a climax, when Li Xue and Lin Feng are about to expose Su Ming's crimes in court, but Su Ming suddenly takes out a document, claiming that this is the latest evidence in the case that year. This document shows that Lin Feng is indeed the murderer of Li Hao, and he also has an accomplice - that is, Wang Xiaochen. It turned out that Wang Xiaochen also participated in the crime, in order to cover up his crime, he played Lin Feng's lawyer and used Li Xue's feelings to obtain more information. Su Ming said the document was a confession written by Wang Xiaochen in prison, and that he had been arrested and confessed to his crimes.
This counter-transfer Li Xue and Lin Feng were taken aback, they couldn't believe that Wang Xiaochen was a double agent. They suspected that the document was forged by Su Ming, but there was no evidence to refute it. The atmosphere in the courtroom was silent, and everyone was waiting for the judge to announce the verdict. At this moment, a voice suddenly sounded: "I can prove that this document is fake!" Everyone turned their heads to look and found that the person who spoke turned out to be Li Hao! It turned out that Li Hao did not really become a vegetative person, but was controlled by Su Ming with drugs. With the help of Wang Xiaochen, Li Hao escaped from the hospital and found Li Xue and Lin Feng. He said he was willing to take responsibility for his crimes and expose Su Ming's conspiracy. Su Ming was shocked by this anti-transfer, he wanted to escape, but was caught by the police. The judge announced the verdict: Su Ming was sentenced to life imprisonment, Lin Feng was acquitted, and Wang Xiaochen was sentenced to three years of probation and judicial compensation.
Ending with a relatively just and peaceful ending, Just Cause is a compelling crime suspense drama that not only presents a complex and twisty story thread, but also explores some profound topics about law, justice and human nature.