S4·E20 Ghost from the Past

Episode recap

In the twentieth episode of the fourth season of FBI, titled Ghost from the Past, the murder of a TSA agent initiates an investigation by the team. Their hunt leads them to a killer who is utilizing drug mules in order to exploit security checkpoints at airports. Concurrently, OA struggles to cope with the aftermath of the sarin gas exposure. In addition to dealing with these physical and psychological effects, he is also managing the emotional toll of the tenth anniversary of the death of his army friend in Afghanistan. The narrative focuses on these parallel developments as the team pursues the perpetrator while OA navigates his personal trauma and remembrance.