Palmer and Sherry clash over the handling of the evidence against Carl. Kim finds herself in a sticky situation with Dan's brother. Jack poses as Alexis and meets with a stranger who has vital information, but an agent with a grudge from Jack's past picks a bad time to get even. Teri and Phil return to the Bauer home, putting themselves in further danger.
Two traitors are uncovered. One is Roger Stanton. The other is Marie Warner, who helped Syed Ali bring the bomb into the country. Jack learns of Ali's location and tries to rescue Kate. Kim and Miguel crash their police escort in order to escape from LA. Kim runs through the woods.
Jack and Ramon's plan hits a snag when a group of inmates takes them hostage. Chloe discovers Jack's addiction and reveals his secret to Kim and Michelle. Palmer begins his debate with Keeler. Kyle decides to kill himself to save Linda.
CTU tracks down the override device and learns the identity of the man behind all of the day's terrorist attacks. Curtis and Jack try to apprehend the suspect before the nuclear plants meltdown. At CTU, Driscoll deals with a personal crisis with her daughter.
Jack Bauer interrogates Henderson's wife, Lynn tries to get his keycard back as terrorists plan to release the nerve gas in a hospital. Tony wakes up and asks about Michelle's fate. Meanwhile the First Lady tries to avoid the President.
Iké Dubaku is captured, but at a tragic cost. His cover nearly blown, Sean Hillinger takes drastic steps to hide his involvement in the day's events. As Jack reflects on the trials of the last few hours, Tony Almeida returns with some ominous news.