Jack witnesses a murder linked to his lengthy undercover assignment; the delivery of a contaminated corpse precedes a threatening call to the FBI. Chase.
Jack and Chase visit the last address of the infected body; Palmer suggests cancelling the debate, but Wayne disagrees, hinting at a vulnerability in their opponent; Hector's location is narrowed down.
Kyle's parents get a clue about his activities; Wayne finds a solution to the problem regarding Anne; Salazar requests another meeting with Annicon; the virus's infection and fatality rates are revised upward.
CTU receives instructions for Salazar's delivery; Kyle and Linda get a glimpse of what they're into; Chase disobeys Jack, who makes a report, and a suggestion, to the president.
Jack's diversion at the prison comes back to bite him; Gael seeks to slow CTU's tracking of Kyle; Kim is rattled by news of Jack's activities; Keeler plays the Anne card at the debate.
After Chappelle takes command at CTU, Chase lobbies him to get Palmer's input on Jack's situation; Kim's emotional state is questioned; Kyle's parents get a prognosis on their son.
Michelle asks Gael to take over for her; Chase gets help in disobeying Chappelle to pursue a lead on Jack's location, where Ramon grows impatient; Anne is contacted by her ex-spouse.
Wayne and the president disagree over Jack's actions, which are explained to Ramon; CTU tries to intercept Chase; Anne gets more than she wants from her ex-husband.
Michael changes the arrangements for the sale; Jack gets an ally; Palmer is summoned by an important supporter; Tony's competence is questioned.
Gael speaks to Jack; Wayne tries his own field op when Milliken flexes his muscle against Palmer; Sergio delivers disturbing news to Hector; Chloe responds to a family emergency.
Emotions carry weight as Palmer makes a deal in his "street fight" with Milliken; Hector's doubts about continuing the operation cause dissension with Ramon; Kim gets a disturbing assignment.
Tensions escalate at CTU with the arrival of a cocky systems analyst and a question about Chloe's baby; Sherry gets the goods on Milliken, but Palmer balks at the price.
Nina takes things in a new direction, and adds a new player; Chloe is out of service when CTU needs her most; Sherry launches a stealth op against Milliken.
Sherry lies to Palmer about seeing Julia; Alvers alters the virus; Nina is introduced to new interrogation techniques, while Jack is also questioned regarding his past infiltration of the Salazars.
CTU IDs the system likely to launch the virus; Amador is chastised by his employer, who's familiar with Jack; the police question Julia without a lawyer present.
Extreme force is ordered to isolate the hotel; Sherry threatens Palmer over Milliken's death; the amount of virus remaining and its altered power is determined; a conspirator makes a deal to tell what he knows.
The link is found between Jack and Saunders, who makes his first demand of Palmer; Jack uses a legal loophole against a new witness; Michelle lobbies to ease the pain of the infected.
Jack prepares Chappelle for his assignment; a hotel guest reports a missing companion who may have left the hotel with the virus; Michelle gives the infected the cold truth, with an option.
Jack urges caution with a new lead and it comes back to bite him; Cole seeks help for his nose; Palmer convenes the cabinet before hearing Saunders' next demand, and ultimate goal.
The president is ordered to leave L.A., and asks the press to help maximize public safety; Jack gives Jane a crash course on her father; the virus affects another CTU operative.
As Saunders keeps him on a tight rein, Tony scurries to cover his tracks, while the rest of CTU suspects another mole; Sherry Palmer makes an offer of assistance.
Michelle tries to unnerve one of her captors; Keeler personally plays his card against Palmer; Tony argues with Saunders over arrangements for their trade.
Jack argues for Tony, who's taken into custody; an implacable Saunders tells the time of the next attacks; Wayne and Foxton have differences on their operation as time runs out, and afterward.
Saunders reveals the B-plan of the last courier, who benefits from a CTU snafu that gives Tony a temporary reprieve as he's called back to the case. Meanwhile, Chase makes decisions about his future.