Ep 21. Day 2: 4:00 A.M.-5:00 A.M.

Jack and Yusuf are taken hostage by Syed Ali's men, but Yusuf sacrifices himself to give Jack an opportunity to escape. Meanwhile, Kate is interrogated by the CTU after it is discovered that she leaked information about the nuclear bomb to her father, who then gave it to his business partner, who in turn sold it to the terrorists. The CTU tracks down the location of the bomb and assembles a team to disarm it, but complications arise when the terrorists gain access to the facility and engage in a shootout with the CTU agents. Meanwhile, President Palmer makes the difficult decision to declare martial law in Los Angeles, invoking the Insurrection Act to deploy military troops to the city to maintain order. As the clock ticks down to the detonation of the bomb, Jack must race against time to retrieve the necessary evidence to prove that Ali is the mastermind behind the attack and prevent a full-scale war between the United States and the Middle East.