Jack and Sherry Palmer prepare for a dangerous meeting with the head of the war conspiracy at the L.A. Coliseum; David Palmer sits in as the Cabinet waits for confirmation of the Cypress Chip's invalidity; the air strike on the Middle East draws nearer; the conspiracy goes to an old agent to put Palmer out of play.

Three years have passed since the events of Day Two. A van deposits a dead body outside the LA Health Unit. The body is infected with a deadly virus. Tony, now in charge of CTU, learns that this is a blackmail tactic to get the US government to release a drug lord, Ramon Salazar, whom Jack has just brought down, before Salazar's brother releases the virus into LA.

Jack and his new partner, Chase Edmunds, prepare to sign a deal with Salazar at the prison. Salazar delivers a mysterious warning to Jack before killing his lawyer.

Palmer is alive and well, and has returned to LA for the first time since the attack three years ago. He is running for re-election and is preparing for an important debate with a rival senator. He is accompanied by his brother, who happens to be his chief of staff and his doctor, who also happens to be his girlfriend.

A young boy, Kyle Singer, is seen examining a large, mysterious bag of white powder. He plans to deliver it to some dealers later that day, but he is 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.

Palmer clears Anne's name with the press, but he finds that he is facing a new problem when his biggest campaign contributor reveals a startling secret about Wayne.

Kim and Michelle worry about Tony's mental ability when he continues to make mistakes.

Jack and the Salazars meet with Amador, but the deal turns sour when Nina Myers appears on the scene and competes for the virus.

Things finally come to an explosive head as Jack, Ramon, Nina and Chase all close in on the virus. But the deal takes an unexpected turn when Amador pulls a fast switch.

Kim becomes suspicious of Chloe when her story about her baby doesn't check out.

Sherry finds a witness who can damage Milliken, but her advantage is short-lived.

Presented with the evidence of Olivia's actions, President Allison Taylor is forced to make a decision between her family and the Presidency. Thanks to Kim Bauer, Janis, Renee and Chloe are able to save Jack and arrest Tony before he can kill Alan Wilson. With Wilson refusing to talk and Jack about to die, the fight is no longer in the field, it's for the hearts and souls of Jack and Renee.