Government agent Jack Bauer (Kiefer Sutherland) finds himself removed from the Counter Terrorist Unit 18 months after his last 24-hour roller-coaster ride. Erin Driscoll (Alberta Watson) heads CTU after firing Jack, who's now firmly ensconced at the office of Secretary of Defense James Heller (William Devane). But as Jack heads to an unexpected meeting with Driscoll, a commuter train explodes, setting off yet another horrific chain of events.