1x9: Billions

: The episode ends with Donnie reappearing only to suffer a medical emergency during a high-pressure interrogation, leaving the investigation in jeopardy Den of Geek. Key Takeaways for Fans

: Donnie Caan, the internal mole for the Feds, vanishes. His absence creates panic for both Axe, who suspects a traitor, and Chuck Rhoades Southern District of New York , whose entire case against Axe Capital depends on Donnie's testimony Den of Geek . Billions 1x9

: Every character, from Chuck to Wendy, begins to reconsider their future as the investigation starts to bleed into their private lives Billions Wiki. : The episode ends with Donnie reappearing only