Former Counter Terrorist Unit agent Jack Bauer begins the season, working as a day-to-day laborer at an oil refinery under the alias "Frank Flynn" in Mojave, California.

Michelle is killed when her car explodes and Tony is critically injured in a secondary explosion but Jack manages to save Chloe.

While searching for the nerve gas, Jack discovers the involvement of James Nathanson and White House Chief of Staff Walt Cummings.

They plan to release nerve gas on Russian soil and use that as an excuse for invoking the military clauses of the treaty, allowing Logan to secure American petroleum interests in Central Asia.

The nerve gas is deployed at Sunrise Hills Shopping Mall (resulting in 10–20 fatalities out of eight-nine hundred shoppers) and Tyler Memorial Hospital (unsuccessfully due to the actions of CTU and Curtis Manning).

When CTU is decontaminated, Jack rushes to the medical room and sees that Henderson apparently killed Tony and escaped.

He is at the center of a conspiracy involving Cummings, Henderson, Nathanson, a mysterious man known as Graem and a group of men who monitor and influence the actions of Logan from an undisclosed location.

Jack and Wayne retrieve a recording that implicates Logan from a bank vault and attempt to turn it over to U.S. Secretary of Defense James Heller.

However, Heller's plan to get Logan to quietly resign backfires when Christopher Henderson uses Audrey as leverage to get the recording from Jack.

Meanwhile, Bierko escapes CTU custody, and uses his last nerve gas container to take over a Russian submarine and gain control of twelve multiple-warhead non-nuclear land-attack missiles, each one capable of wiping out several city blocks.

With the help of the First Lady, Mike Novick, Aaron Pierce, and Chloe, Jack is able to hijack Marine One and attempts to force Logan to confess.

[25] Spoilers released by Ain't It Cool News revealed that two major characters including a politician would die in the premiere episode.

The website's critical consensus reads, "24 defies the law of diminishing returns with a spectacular fifth season that features White House intrigue, some of the most harrowing set-pieces in the series yet, and a heroically committed performance by Kiefer Sutherland.

[30] likewise USA Today gave the episode a positive review, and praised Kiefer Sutherland, who portrayed Jack Bauer.

[31] The New York Times also reacted positively, saying, "all the villains, be they Islamic fundamentalists, drug smugglers, American oil brokers or Russian separatists, keep picking Los Angeles as a target for attack.