Jack Bauer (Kiefer Sutherland) and his team of agents uncover a plot to assassinate a presidential candidate.
Meredith and Cristina rely on each other as they face more responsibilities at their respective hospitals and cope with life after the plane crash; Cristina helps Dr. Thomas with a challenging heart surgery.
Jack tries to determine why an airliner exploded over the Mojave Desert, while he continues searching for the assassin who made an attempt on Sen. Palmer's life.
Kimberly and Janet find themselves in danger; Jack obtains a key card that could lead to the terrorist organisation.
Jack suspects someone at CTU might be involved in the assassination attempt; Palmer decides to make an ill-advised public appearance.
