The Treasury Department’s Federal Bureau of Narcotics was targeting Billie over her groundbreaking song “Strange Fruit,” which is known as the first great protest song. “Strange Fruit” is an unforgettable protest against the inhumanity of racism, and Billie sang about racist lynchings, which drew a lot of attention to the murders of Blacks in the South. The FBI feared that her song would compel people to protest, and they needed to step in somehow.
After rumors spread that the singer was using heroin, Jimmy Fletcher was assigned to track Billie’s every move by the head of the Federal Bureau of Narcotics, Harry Anslinger (played by Garrett Hedlund in the biopic).
Harry hated hiring Black agents, but he knew Jimmy was the answer because if he sent a white man into Harlem and Baltimore, they would stand out. Basically, Jimmy’s job was to infiltrate Billie’s circle. He was allowed by the bureau to deal drugs in order to keep his cover as an agent.
He would carry large amounts of drugs with him, and he gained the confidence of the people he was secretly plotting to arrest. Jimmy first met Billie at her brother-in-law’s apartment where they were supposedly indulging in a night of drugs and alcohol. It did not take long for Jimmy to be captivated by the jazz icon, making for an extremely complicated relationship.
Source : https://www.distractify.com/p/jimmy-fletcher-billie-holiday