Warning: This story contains plot spoilers
By Kevin Young
Entertainment reporter, BBC News
The new series of real-time TV drama 24 begins this Sunday in the US and on 21 January in the UK.
The show, which stars Kiefer Sutherland, has won critical acclaim for its topical, fast-moving storylines.
Kiefer Sutherland stars as one-man crime-fighting machine Jack Bauer
But the pace can also leave infrequent viewers struggling to keep up with the changing characters and terrorist plots.
If you have missed any of the previous five seasons, or feel daunted at the prospect of watching 120 episodes from the start, our quick recap will bring you up to date ahead of the twists and turns of Day 6.
We meet Jack Bauer, a special agent with the Counter-Terrorism Unit (CTU) in Los Angeles.
Today, we learn, will be the longest day of his life.
The kidnapping is organised by a man Bauer once tried to capture
Jack's wife Teri and daughter Kim are held hostage by terrorists wanting to kill Democrat politician David Palmer on the day he runs in the US presidential primaries.
The kidnappers demand that Jack assassinates David, threatening his family unless he complies.
They also have a mole within CTU.
She turns out to be Nina Myers, Bauer's former lover and now the girlfriend of senior CTU figure Tony Almeida.
Nina Myers is introduced as an integral part of the 24 storyline
David Palmer's death is averted but Teri works out that Nina is the informer.
Teri is promptly shot dead by Nina, who is then captured.
It is the kind of plot twist for which 24 will become famous.
Jack Bauer has left the Counter-Terrorism Unit (CTU), while Kim has recovered from her kidnap ordeal to become a nanny.
She goes on the run to rescue a young girl in her care from an abusive father, but does so on the day that terrorists threaten to detonate a nuclear bomb in the US.
Kim Bauer (left) is on the run from Megan Matheson's abusive father
Jack becomes embroiled in both storylines.
New character Kate Warner discovers that her sister is about to marry a man with connections to the planned bombing and helps CTU.
Nina Myers is employed by the baddies to share her knowledge of CTU, and double-crosses Jack to take him hostage.
Jack's efforts mean the bomb is found and former CTU director George Mason flies the device into the desert on a suicide mission.
Kate Warner (left) becomes a key witness as agents chase the bomb
David Palmer is now the US president but is removed from office by Cabinet members who lose faith in his handling of the bomb plot.
He is reinstated, but the series ends with an assassination attempt - he collapses after shaking the hand of a woman who has passed on a lethal substance.
Jack Bauer is back as a Counter-Terrorism Unit (CTU) agent. But he is addicted to heroin, the relationship he developed with Kate Warner is over, and he has a new partner at work, Chase Edmunds.
Chase is going out with Jack's daughter Kim, who now also works for CTU.
Interfering Sherry Palmer (left) is murdered in an act of revenge
Jack is upset about this and it distracts him as he searches for terrorists who want to release a deadly virus in Los Angeles.
Nina Myers returns, trying to buy the virus from shady characters in Mexico. Jack finds her and she tricks him into infecting CTU's computer system.
David Palmer has survived the attempt on his life but decides not to seek re-election when a political scandal hits his family, ending in the murder of his wife.
Nina holds Kim at gunpoint but Jack finds them and shoots Nina.
Jack is forced into drastic action when the virus is attached to Chase
Finally, his nemesis is dead.
A container holding the virus ends up being attached to Chase's arm.
Jack hacks off the limb so the substance can be made safe. Happily for Jack and Kim, Chase's arm is sewn back on in hospital.
Jack Bauer has been fired by the Counter-Terrorism Unit (CTU) and now works for Defense Secretary James Heller.
He has to keep quiet about his new girlfriend, Audrey Raines, as she is Heller's daughter.
The execution of James Heller (left) is to be shown online by terrorists
Turkish terrorist Habib Marwan kidnaps Audrey and her father and plans to execute them.
He is also behind several plots, including a meltdown at power plants and an attack on Air Force One.
US Vice-President Charles Logan takes over as leader following the plane crash.
Jack manages to foil an attempt to steal and launch a nuclear missile but a botched raid from earlier in the day comes back to haunt him.
Former CTU boss Tony Almeida (left) returns to help find terrorists
He went to catch a renegade official at the Chinese consultate, but this led to the death of the country's consul.
The Chinese are furious and want to kill Jack, but colleagues help him to fake his own death and he walks off into the sunset.
Jack Bauer is living as Frank Flynn and is asked to help foil terrorists targeting the Russian president's visit to the US.
The four people who saw Jack fake his own death become targets themselves. Ex-president David Palmer is assassinated, with Jack framed as the killer.
Ex-president David Palmer (right) is killed by a sniper as the day begins
Jack's former Counter-Terrorism Unit (CTU) colleagues Michelle Dessler and Tony Almeida are also murdered, but IT geek Chloe O'Brian is saved, with Jack's help.
The terrorists take hostages at an airport, then steal nerve gas and release it at a shopping centre and CTU headquarters.
David Palmer was killed because he found out that the terrorists' plot was part of a government conspiracy, with President Charles Logan at its heart.
President Charles Logan (left) is involved in the terrorists' plot
Logan is arrested after Jack stops a submarine attack and kills the terrorists.
But as Jack is reunited with girlfriend Audrey Raines, he is lured away by Chinese agents in revenge for the botched raid on their consulate, and is held captive on a cargo ship.
The sixth series of 24 launches on Fox across the US on Sunday 14 January.
It will be shown on Sky One in the UK from Sunday 21 January.