W. Mark Felt spent 31 years inside the FBI, rising to its number-three post, and became Deep Throat, the anonymous source who guided reporters through the Watergate scandal.

This episode follows his path from investigating toilet-tissue advertising to running counterespionage, guarding Hoover's secret files, and leaking to Bob Woodward, all while authorizing illegal break-ins himself.

• A first federal assignment probing Red Cross toilet-tissue claims
• Running the WWII double agent code-named Peasant
• Being passed over for FBI director in favor of L. Patrick Gray
• The flowerpot and parking-garage signals used with Bob Woodward
• His conviction for black-bag jobs and Reagan's pardon