Contains spoilers for this episode and season finale.
A flashback follows Anna as she gives birth to Ellie in an abandoned house while an infected attacks. Anna kills it, then discovers she has been bitten; after the attack, she cuts the umbilical cord. When Marlene arrives, Anna falsely says she cut the cord before the attack, concealing when the bite occurred. She asks Marlene to take the baby. Marlene carries Ellie away and shoots Anna. In the present, Joel and Ellie reach Salt Lake City. They encounter a herd of giraffes in an abandoned building, but their walk is interrupted when Fireflies stun them and take them to the hospital.
Marlene explains that the Fireflies plan to remove the infected growth in Ellie’s brain and study it for a possible cure, a procedure that will kill her. Joel refuses to accept the decision. After guards escort him out, he fights through the hospital, reaches the operating room and carries Ellie away. He kills Marlene when she tries to stop him. On the drive toward Jackson, Ellie asks what happened. Joel tells her the Fireflies had found other immune people and abandoned the cure effort. Ellie recounts her first bite alongside Riley, then asks Joel to swear his account is true. He does, and she answers, “Okay.”