Four years later Jack Bauer is considered a terrorist on the run when he is captured by the CIA in London. 

Agent Kate Morgan who is getting transferred back to the States because her husband was selling secrets to the Chinese figures out that Jack intentionally got caught in order to save Chloe O'Brien who is being interrogated/tortured by Special Activities. 

Jack escapes with Chloe but all of London is looking for them.

President Heller is in London working on a treaty, despite protestors upset about US drone use. Heller is suffering from what appears to be Alzheimer's and shares with daughter Audrey that it's progressing faster than expected.

Mark Boudreau is married to Audrey. He knows about the Jack Bauer situation and doesn't want Audrey or the President to hear about it. He wants to hand Jack over to the Russians so his wife never has to hear his name again.

In Afghanistan, a drone is taken over by unknown forces and bombs an American/British convoy.