Spoilers for this episode.
Jack brings Nina to CTU, where Chappelle orders him to undergo a medical examination and answer questions about his heroin use. Kim is shaken by Nina's return and asks why her father hid his addiction. Chase also has an explanation to give: his former girlfriend recently left him with their daughter, and Chloe has been helping him care for the baby.
Tony questions Nina about Alvers while Michelle watches from the adjoining room. Nina brings up their former relationship and tries to unsettle him. CTU notices a physical reaction when Tony mentions Alvers's medical records, suggesting Nina knows him more closely than she admits. Elsewhere, Amador hands Alvers the real virus. Sherry initially denies visiting Milliken, then admits to Palmer that she was present when he suffered his heart attack.
During a harsher interrogation, Nina deliberately drives a needle deeper into her neck, forcing the staff to take her to the clinic. She blocks the anaesthetic, pretends to be unconscious and escapes after killing medical personnel. Kim takes a dead guard's gun and confronts her in a control room. Jack arrives and shoots Nina in the shoulder before ordering Kim away. Left alone with Nina, he fires the shots that kill her. The search for Amador continues without the prisoner CTU hoped would lead them to him.