Donald Trump takes office as the FBI investigates Hillary Clinton and Russian election interference. When Director James Comey refuses to pledge loyalty, Trump fires him, raising questions about the FBI's independence and national security.

During his tenure, J. Edgar Hoover transforms the FBI into a law-enforcement powerhouse — and a hub of unchecked surveillance. When Richard Nixon pressures him to expand domestic spying, Hoover is forced to defend the Bureau's independence.

In the wake of 9/11, George W. Bush and new FBI Director Robert Mueller unite to prevent another attack, but their close alignment ushers in the Patriot Act and an era of surveillance and government overreach not seen since Hoover's reign.

In the post-Cold War era, Bill Clinton appoints Louis Freeh as FBI Director; their relationship strains amid the controversy of the Lewinsky investigation and ruptures permanently at a moment when the country can least afford the breakdown.