Ep 21. Day 4: 3:00 A.M.-4:00 A.M.

In episode 21 of season four of 24, titled Day 4: 3:00 A.M.-4:00 A.M., the tension is at an all-time high as Jack Bauer continues to race against the clock to prevent an imminent terrorist attack.

As the episode begins, Jack and his team are hot on the trail of terrorist mastermind Habib Marwan, who has managed to gain control of the country's nuclear power plants. With the threat of a nuclear meltdown looming, Jack must work quickly to stop Marwan and his team of accomplices before it's too late.

Meanwhile, back at CTU, tensions are running high as Audrey Raines deals with the aftermath of her father's death. To make matters worse, she is forced to confront her ex-husband, Paul, who is still struggling to come to terms with their divorce.

As the hours tick by, the situation grows more dire by the minute. With the fate of the country hanging in the balance, Jack must put his life on the line once again to stop Marwan and his associates from carrying out their deadly plan.

In a heart-stopping climax, Jack and his team finally track down Marwan's location, setting the stage for a fierce showdown between the two sides. With bullets flying and explosions erupting around them, the fate of the world hangs in the balance as Jack and Marwan face off in a brutal fight to the death.

As the episode draws to a close, the dust settles on the battlefield and Jack is left to pick up the pieces of the past 24 hours. Though his mission was a success, the toll it has taken on him is clear to see as he struggles to come to grips with the losses he has suffered along the way.

Overall, Day 4: 3:00 A.M.-4:00 A.M. is a gripping and intense episode of 24 that will leave viewers on the edge of their seats from start to finish. With non-stop action and heart-pounding suspense, this is one episode that fans of the series won't want to miss.