After the last terrorist attack, the government was not satisfied with CTU's solution to the terrorist incident, so it finally decided to disband CTU. Jack Bauer (Kiefer Sutherland) was also investigated for using illegal means such as torture to prevent terrorist attacks. Jack thought he would spend the rest of his life in prison, but the appearance of his former colleague Tony (Carlos Bernard) who came back from the dead completely disrupted Jack's current life. Tony hopes that Jack can work with him to investigate another terrorist attack on the American road. As the investigation continues to deepen, Jack feels that Tony around him is becoming more and more unpredictable. Jack always feels that Tony has something he didn't tell him clearly. Because of the new president's trust in Jack, their investigation is full of crises, but it is still going smoothly. However, in the end, Jack finally discovered that the mastermind behind the terrorist attack was Tony, his friend who had been fighting side by side with him...