On the surface, Black Bird is a straightforward true crime drama that uses a murder mystery to drive its narrative — but between its realistic police procedures and poignant finale, the Black Bird ending explains the ways in which a gruesome crime affects many lives. Black Bird primarily unfolds from James "Jimmy" Keene's perspective, whose real-life memoir is the inspiration behind the show's premise. The show begins with Jimmy getting a 10-year prison sentence for pretty crimes. However, the FBI makes him an offer: if he can make suspected serial killer Larry Hall confess, Jimmy will be released from prison.

https://screenrant.com/black-bird-show-ending-explained/