Spoilers for this episode.
Jack and Chase find Nina in the woods and take her alive, hoping she can lead them to the virus. On the flight back to Los Angeles, she names Marcus Alvers as Amador's local contact. CTU confirms that the two men have worked together, giving Jack a reason to keep questioning her despite everything she has done to his family.
Nina offers a telephone route to Alvers in return for Jack's support with prosecutors. Following her instructions instead activates a computer worm she planted during her time at CTU. She demands that the plane return to Mexico and promises a shutdown code once she is free. Tony brings Chloe back to work on the damaged network, even though Chappelle has detained her over the baby she brought into the building.
Sherry visits Julia Milliken and takes Alan's phone to investigate his calls. When Alan confronts them and suffers a medical emergency, Sherry stops Julia from giving him his medication. He dies, and Sherry pressures Julia to conceal her visit. Meanwhile, Tony orders Jack's plane back to Mexico as the worm spreads. Jack forces the pilot to continue toward Los Angeles. Chloe stops the worm before Nina can secure her freedom, then admits to Chappelle that Chase is the baby's father.