Near the start of the episode, President Heller and Jack Bauer have a heated discussion about Heller's plan to hand himself over to Margot Al-Harazi. Heller argues that his choice to sacrifice himself is a personal, not a state, decision. This scene is the heart of the episode, and the rest is the execution.
Heller begins by showing Jack a recording of the conversation with Margot Al-Harazi, where Heller asks her to prove her supposed abhorrence of shedding "innocent blood" by promising to destroy all the drones if he lets her shed his blood. In response, Jack growls that they are not to negotiate with terrorists. Here Heller shows his resignation letter and states the matter is not an issue of national policy, but a personal decision.
In this moment Heller wishes Jack to separate him from his office and focus on his personal, moral choice. Heller, though president, is just a man, one who has to live with the choices he makes. It is difficult for Jack, who has a tremendous respect for the office (even after his encounters with President Logan), to listen, so he starts to walk out.
Before Jack can leave, Heller makes the situation even more personal by confessing to his fight with Alzheimer's. When Jack counters this crisis is not about Heller, the President yells at him, referencing the thousands who will die if the Al-Harazi's deliver on their threat, claiming that Jack would do the same thing if he were in Heller's shoes, in his position (office): "Face it, Son, you and I are the only chance they have."
Heller is asking Jack to approach this situation personally too. Jack starts to relent, asking if the President has told Audrey, and then proposing they'll need one other person to pull it off. When the President picks Mark, the episode pulls these three together into an unexpected team.
Also resistant when he first hears, Mark voices Margot Al-Harazi has made it personal. Heller says that's the point; she'll no longer want to destroy half of London if she has him. Mark finally joins when Heller asks him not to deny him one last service. It is a plea that on first glance looks like an appeal to his role as chief-of-staff, but the way Heller has framed it--"you've been a loyal friend and supporter"--actually makes it just as much a personal request.
Later, Mark suggests to Jack they need to find a way to trust each other, suggesting a more personal connection, but Jack is all official here, saying the presidential directive is what motivates him. Stuck in the personal, Mark whispers Audrey will never forgive him for carrying out this plan.
When Heller slips into his daughter's office, he seeks to have one personal moment with her, asking her to show him the photograph she has of them together, at the beach with her mother, when they were younger. She shares a brief moment with him, stating the photograph gave her a sense of security when she was a girl (that nothing bad would happen as long as she had it). After asking if he is well, she then tells him she has to get back to work. In the moment, not realizing his intentions, she chooses her office.
When Audrey later finds the note from her father--viewers do not see her finding it, but Mark's discovery of her after she's read it--she, of course, does make it personal. Because he does not feign surprise, Audrey discerns Mark knew about the plan. She immediately says he should have told her because he is her husband. She says Mark is complicit in her father's death, that she will never trust him again.
The familial connection is slightly different from the personal, but here the familial would be grouped as personal, private, and set in tension with one's work, profession, office. Mark counters her argument, by voicing he has done exactly what her dad wanted. He hated to do it, he thought her dad was the "greatest man he ever knew," but he did what her father asked of him. Finally, he tells her they will remain quiet about it because those were her father's wishes.
In 24 fashion, there are other subplots running along: Jordan's confrontation with the assassin (leaving him bleeding out from a wound), the Al-Harazi's wondering if Heller will keep his word (and Margot saying she'll keep her word to show the world "justice" has been done), and Chloe trying to work out a last-minute save by decrypting Naveed's disk drive (which Kate gets out of Simone, upon Jack's request, by pressuring doctors at gunpoint to revive her despite her critical condition). But this episode is fundamentally about Heller's choice and those characters around him who are most personally affected by it.
At Wembley Stadium the President offers Jack a gift, a presidential pardon of all charges from four years ago and from the current day, so that Jack can go home. Still resistant, Jack responds that he is not looking for a pardon, particularly for handing Heller over to his death. Although Heller says this decision is the "right way to go," Jack still insists it is "wrong." In this moment we know Jack will be seeking revenge in future episodes.
When Margot Al-Harazi fires the drone missile, the nightmare apparently becomes real; Heller appears to sacrifice himself. Since the ticking clock was not silent at the end of the episode, many have begun to theorize whether the writers have tricked viewers. Did Chloe hack the video feed of the drone to fool the Al-Harazi's? In the next hour, the writers could turn either way. Scenes of sacrifice are also part of 24, and I think sacrifice would fit the tone of the season better, but we'll see whether there was a subterfuge.
Either way, it looks like Heller was willing to hand himself over to this evil, thinking of saving ten of thousands of lives, sharing the same motivating factor as Jack. Jack earlier risked his and Kate's lives, with slim chance of survival, but now he resisted letting Heller walk into a no-chance scenario. Did Jack resist on an official or personal level?
Most likely, it was on both fronts. Jack did not want to hand over the President of the United States to a terrorist, and he did not want to hand over Audrey's father, a man he deeply respected despite their differences.
This episode is a prime example of the legacy of 24, and we can celebrate with the production team the reaching of the 200th-episode milestone. It was a moving hour.