24 (season 1)
Season 1 begins and ends at 12:00 AM, and occurs on the day of the California presidential primary. Jack Bauer must protect Senator David Palmer from an assassination plot, and rescue his family from those responsible for the plot, who seek retribution for Jack's involvement with a covert U.S. mission in the Balkans.
Season 2
24 (season 2)
Season 2 begins and ends at 8:00 AM. Jack must stop a nuclear bomb from detonating in Los Angeles, then assist President David Palmer in proving who is responsible for the threat.
Season 3
24 (season 3)
Season 3 begins and ends at 1:00 PM. While struggling with heroin addiction, Jack must re-infiltrate a Mexican drug cartel in order to keep it from acquiring a deadly virus. Jack must then stop the mastermind behind the virus from releasing it.
Season 4
24 (season 4)
Season 4 begins and ends at 7:00 AM. Jack must save the lives of Secretary Heller and his daughter Audrey Raines (with whom Jack is romantically involved) when they are kidnapped by terrorists. The same terrorists then launch further attacks against America, and Jack is forced to use unorthodox methods to stop them, methods that will have long-term consequences for both Jack and the U.S.
Season 5
24 (season 5)
Season 5 begins and ends at 7:00 AM. Jack is believed to be dead by everyone except a few of his closest friends. Terrorists with connections to the U.S. government attempt to steal nerve gas in order to protect US oil interests in Asia, and Jack must resurface to stop them.
Season 6
24 (season 6)
Season 6 begins and ends at 6:00 AM. Jack is released after being tortured in a Chinese prison for twenty months. Terrorists attempt to set off suitcase nuclear devices in the United States and Jack must stop them as well as prevent sensitive circuitry from falling into the hands of the Chinese to prevent war between the U.S. and Russia.
Season 7
24 (season 7)
Season 7 will begin and end at 7:00AM, and will begin airing in the United States in January 2008. Kiefer Sutherland has been signed to stay with the show through 2009. The season is to be more personal than previous seasons.[21] It will also feature the show's first female president, Allison Taylor, played by actress Cherry Jones,[22] as well as the return of Mary Lynn Rajskub.