So, in the first part of Season 4, Jack is now working for the Secretary of Defense, James Heller, and is dating his daughter, Audrey. Heller and Audrey are kidnapped at the end of episode 1 and then Jack rescues them less than 5 hours later. Of course, Driscoll didn’t want to work with Jack at first and resisted his attempts.
While everyone thought that the purpose of Heller’s kidnapping was to humiliate him and the country through a forced confession and execution, it turns out the whole thing was a diversion from the real purpose – Marwan using an override device to access the network of nuclear power plants across the country.