Well, I figure if anyone comes into this thread, they better expect spoilers.....
Well, David Palmer gets assassinated about 2 minutes into the show. Tony and Michelle are doing their own thing, running their own business, but she insists on heading back to CTU to lend a hand, given that they had done many profiles on David Palmer's enemies in the past. Tony is reluctant, and during his hesitation, Michelle goes kaboom to a car bomb. Tony goes out to pull her out, and gets put into critical condition as residual explosions happen.
Chloe is off to work as well, and Edgar gives her a dingle about what has happened. Chloe, realizing she's the last person alive that knows that Jack is still alive, freaks out....rightfully so. She sees some people in a van and starts to run. She was able to evade her captors, and contacts Jack on a pay phone. Curious as to what's going on, angry that his good friend Palmer is dead, and willing to save his friend Chloe's life...he hijacks a helicopter and heads back to meet her and figure out WTF is going on.