The entire squad race against the clock to uncover the clues and solve the puzzles scattered throughout the city by a serial killer, who is taunting them to find him and the next victims on his list.
An eighth day of pulse-pounding action begins as a retired Jack Bauer is unwillingly entangled in an assassination plot against visiting president, Omar Hassan.
CTU apprehends a suspect in the thickening assassination plot, but Chloe's convinced they've got the wrong person. Meanwhile, Dana's past returns to haunt her.