1:00 p.m.-2:00 p.m.

Three years have passed since the events of "Day 2." Tony (now in charge of CTU) learns that terrorists are plotting to unleash a deadly virus in Los Angeles unless a drug lord named Ramon Salazar (whom Jack has just brought down) is released within six hours. Unaware of this development, Jack and his new partner, Chase Edmunds, prepare to sign a deal with Salazar at the prison. President David Palmer is running for re-election and is preparing for an important debate with a rival senator. He is accompanied by his brother Wayne, who happens to be his chief of staff, and his doctor, Anne Packard, who also happens to be his girlfriend. A teenager named Kyle Singer is seen examining a large, mysterious bag of white powder. He plans to deliver the drugs to some dealers later that day, but he is secretly being watched by Salazar's men. Kim now works at CTU and has been dating Chase for three months. Kim wants to tell her father, but Jack has a mysterious health problem that may make things more complicated.

2:00 p.m.-3:00 p.m.

After raiding a crackhouse, Jack and Chase learn of a lead to the possible whereabouts of the virus. Wayne Palmer approaches David with potentially damaging information about Anne.

3:00 p.m.-4:00 p.m.

Jack and Hector Salazar's men both search for Kyle, who is thought to be unknowingly carrying the virus in the bag of drugs that he is planning to sell. Meanwhile, David Palmer and his brother argue over the implications of Anne's past. Tony leads an operation to get Kyle at a mall downtown, but tragedy strikes when Salazar's contact gets there first.

4:00 p.m.-5:00 p.m.

Michelle is torn by personal and professional obligations when she must take charge of CTU after Tony's injury. Kyle and his girlfriend Linda are captured by Hector Salazar's men. Jack and Palmer have a secret conversation, leading Jack to take drastic action in the face of the Salazars' threat. However, Jack's plans are soon complicated when Chase unintentionally gets in the way.

5:00 p.m.-6:00 p.m.

Jack's efforts to break Ramon out of prison go awry when they are captured by a group of inmates during the riot. Palmer begins his debate with Keeler.

6:00 p.m.-7:00 p.m.

Jack and Ramon struggle to evade the authorities, while Palmer's debate with Keeler comes to an abrupt ending. Kim finds out that CTU agent Gael Ortega is secretly working with Hector Salazar.

7:00 p.m.-8:00 p.m.

Jack is held hostage by Ramon on the flight to Mexico. Anne is given a chance to clear her name, while Chase defies Chappelle's orders and heads down to Mexico to rescue Jack. Against doctor's orders, Tony returns from the hospital and, to the shock of everyone, demands to speak with Gael Ortega about an unspecified matter of national security.

8:00 p.m.-9:00 p.m.

Palmer and Chappelle view a message from Jack, explaining his undercover work with the Salazars and the involvement of Tony and Gael in a top-secret sting operation that has been planned out by the three of them for several months. Totally unaware of the stunning development at CTU, Chase arrives in Mexico to rescue Jack. While the Salazar brothers argue over whether or not to enlist Jack's help in making the deal, Bauer contacts Michael Amador: the man in possession of the virus.

9:00 p.m.-10:00 p.m.

Palmer clears Anne's name with the press, but he soon faces an even worse problem involving his biggest campaign contributor. Kim and Michelle worry about Tony's ability to run CTU. Jack and the Salazars' meeting with Amador turns hostile when Nina Myers suddenly appears on the scene.

10:00 p.m.-11:00 p.m.

Claudia, Hector Salazar's girlfriend, manages to free Chase from his captors, but she pays a high price for her efforts. Palmer calls on his ex-wife Sherry for help against Milliken, who is on the warpath against his presidency. Jack and the Salazars track down Nina in hopes of intercepting the virus.

11:00 p.m.-12:00 a.m.

Jack forces Nina to work with him in order to get the virus from Amador. Chase remains in Mexico to help with the capture of the virus. Both Nina and Jack are forced to watch and wait as Ramon and Hector continue to argue over whether or not to go through with the deal.

12:00 a.m.-1:00 a.m.

Sherry finds a witness who can damage Milliken, but her advantage is shortlived. The situation in Mexico comes to an explosive head as Jack, Ramon, Nina, and Chase all simultaneously close in on the virus. But the deal takes an unexpected turn when Amador plays them all for fools.

1:00 a.m.-2:00 a.m.

Amador hops on a jet to Los Angeles still in possession of the real virus. Jack and Chase interrogate Nina, who tells them that they should start looking for a man named Marcus Alvers that Amador may be planning to meet with. However, not all of Nina's information is as helpful. Chappelle becomes suspicious of Chloe when she refuses to answer questions about the baby. Sherry takes her battle directly to the Milliken residence.

2:00 a.m.-3:00 a.m.

Tony interrogates Nina about Alvers' location. Palmer confronts Sherry when he finds out that Alan Milliken is dead, while a hysterical Julia begs Wayne for help.

3:00 a.m.-4:00 a.m.

Chappelle threatens to pull Jack from the effort to find the virus after he kills Nina Myers. Amador and Alvers meet with Stephen Saunders, the mastermind behind the terrorist strike. Saunders orders that the virus be unleashed within the hour. Michelle and Gael locate the target area and must stop Alvers from releasing the virus into a hotel ventilation system. Suspicious detectives turn up the heat on Julia Milliken.

4:00 a.m.-5:00 a.m.

Michelle faces a mob riot at the virus-contaminated hotel. The Chief of Police questions President Palmer about Sherry's whereabouts during the night. Jack suspects that interrogating Amador may not be the best way to find out what he knows.

5:00 a.m.-6:00 a.m.

Stephen Saunders tells Palmer that the virus will be released all across the country unless his demands are met. The villain's first assignment for Palmer creates little chaos- or so it appears. Jack learns of a woman who can lead him to Saunders. Gael's symptoms start to develop after he is infected with the virus. Saunder's second assignment for Palmer is far more troubling than the first.

6:00 a.m.-7:00 a.m.

With Chappelle's life on the line, Jack and Chase race against time to capture Saunders before 7:00 AM- the deadline for his next demand. Michelle begins a frantic search when she learns that an infected hotel guest may have slipped through her fingers. Jack shoots Chapelle.

7:00 a.m.-8:00 a.m.

Jack reluctantly works with Kim on an undercover job that may help them interrogate Saunders' daughter. Palmer informs his cabinet of the new developments concerning the virus crisis, while Saunders gives him a third, and most outrageous, assignment. Chase tracks down the infected man who left the hotel and learns that the virus is spreading to the general public.

8:00 a.m.-9:00 a.m.

Jack attempts to use Saunders' daughter Jane as leverage to gain control of the virus. Tony finds himself in an impossible situation when Saunders exploits his only weakness.

9:00 a.m.-10:00 a.m.

At CTU, Jack and Chloe become suspicious of Tony, who plans to trade Jane Saunders to her father in exchange for Michelle. Sherry meets with Presidential Candidate John Keeler and proposes a most-devious agreement.

10:00 a.m.-11:00 a.m.

Jack and Tony clash as the time for the hostage exchange involving Jane and Michelle draws near. Senator Keeler confronts Palmer and demands his resignation. Meanwhile, Wayne begins a secret operation against Sherry after he realises that she has turned on David yet again.

11:00 a.m.-12:00 p.m.

Jack proves he will go to any length necessary in order to make Saunders tell him the locations of the remaining dealy vials. Tragedy strikes when Wayne breaks into Sherry Palmer's home attempting to steal the incriminating evidence against the president. Tony finds himself facing a harsh penalty as a result of his effort to save Michelle. Jack learns that even with Saunders in custody, the bio-threat against the country is far from over.

12:00 p.m.-1:00 p.m.

In downtown Los Angeles, Jack and Chase pursue Rabens, who is in possession of the final vials. Tony is able to help Jack one last time before he is taken into custody. Even the successful foiling of the entire terrorist plot does not prevent President David Palmer from making a stunning career choice.