Jack is back for Day 3 - this time, the threat is biological. Jack worked undercover as a drug addict trying to bring down Ramone Salazar, one of the drug underworld's most dangerous criminals. Imprisoned and facing trial, Salazar has a way out - through his brother Hector. Jack must fight against his own drug addiction, which he is trying to kick and against the threat of a weaponised virus being unleashed in major US cities.

Kim is in a relationship with Jack's partner, Chase Edmonds, and is trying to convince him to tell Jack about the two of them. But he isn't sure he has the courage to do so, knowing how protective Jack is of his daughter.

Meanwhile, in Washington, President Palmer, recovered from an attempt on his life 3 years previously, is in a race to stay in power and faces a political crisis when his opponent gets personal with his girlfriend and also has to try and maintain the biological threat.

Season 3 is by far the best yet, with drama all round. Can CTU survive it's toughest day to date? Or will morale cave as Tony and Michelle fight to maintain their relationship, Jack fights against his habit and the President fights against political pressure. It's a race against time and only Jack Bauer can save the day.