Three years later; CTU receives a threat that Mexican drug lord Hector Salazar is planning on releasing a deadly contagious virus in LA unless Jack gets his brother Ramon ...

An hour after an infected body is dropped off at the CDC Jack and Chase begin to trace its last known locations while CTU tracks down drug dealers in East LA. President P ...

Tony and one of Salazar's cronies close in on a young drug trafficker who may be unknowingly carrying the virus. Jack informs Kyle Singer's parents that he may be infecte ...

Jack asks for President Palmer's permission to go deep undercover and get Ramon out of prison after CTU looses track of Kyle Singer. While Jack prepares to get Ramon out ...

Jack and Ramon are captured by dangerous prison inmates after trying to escape. President Palmer begins his debate with Senator Keeler. At CTU, Chloe O'Brian discovers ev ...

Jack and Ramon try evade military helicopters when they make a run for a plane scheduled to leave for Mexico. Palmer cancels the debate. Kyle Singer learns that he is not ...

Ramon holds Jack hostage as they fly down to Mexico. Regional Director Chappelle interrogates Gael; Tony returns prematurely to CTU to reveal Gael's true allegiance. Chas ...

Jack tries to regain the Salazars' trust when they make it to Mexico. President Palmer is angry with Tony over being left out of a secret operation. Chase is captured by ...

A snag in the sale of the virus leads the Salazars to question Jack's motivations and as a result they put his allegiances to the test. Claudia works to help Chase escape ...

In order to get closer to the virus, Jack tries to make Nina believe he still has feelings for her. Wayne tries to gain the trust of Julia Milliken when Alan Milliken sta ...

Jack and Nina prepare to meet with Amador, the man selling the virus; CTU organizes an ambush. Ramon and Hector have a falling out. President Palmer asks his ex wife Sher ...

Jack and Nina are double-crossed when Ramon steals the virus during the exchange with Amador. Sherry gains a short-lived advantage in dealing with Alan Milliken. ...

When she's captured by Jack and Chase, Nina unleashes a self repeating worm in CTU's computer system that cuts off inter-agency connectivity and endangers undercover CTU ...

Regional Director Chappelle forces Jack to undergo a medical evaluation for his heroin addiction. Tony interrogates Nina Meyers. Julia Milliken confronts Sherry after Ala ...

Amador and his people receive orders from their client to release the virus in the Chandler Plaza Hotel. Jack closes in on Amador but it's too late. Michelle and Gael ale ...

After the interrogation goes nowhere, Jack and Chase let Amador escape hoping he will lead them to his client's location. Michelle places the hotel under quarantine and m ...

President Palmer gives into Stephen Saunders's strange demand of placing an seemingly nondescript phrase into a speech in the hopes of delaying another viral outbreak. Mi ...

Jack has to comply with another one of Saunders' demands: the death of Regional Director Ryan Chappelle. Michelle discovers that one of the infected hotel patrons got out ...

Jack learns that Saunders' has a daughter attending a local LA college and that the only possible match for a bait and switch operation is his daughter Kim. Palmer inform ...

Jack uses Saunders' daughter as leverage in attempt to control the virus. Palmer maneuvers around a confused and angry press. Michelle awaits the result of a test to see ...

Tony works covertly to find a way to get Jane Saunders out of CTU and deliver her to Saunders before Jack and Chase find him. Senator Keeler receives some damaging inform ...

Jack and Tony clash as they wait for the time of hostage exchange with Saunders. Senator Keeler confronts President Palmer about the Milliken cover-up while Wayne initiat ...

Jack and Chase try to track down the location of vials containing the virus. Wayne breaks into Sherry's house to get incriminating evidence as a paranoid Julia Milliken c ...

Jack and Chase corner Saunders' henchman Arthur Rabens in an active public school. Tony faces losing command of CTU and treason charges for saving Michelle. An emotionall ...