You’ve never heard of her, but somewhere in America, a top-secret investigator known as the Savant is infiltrating online hate groups to take down the most violent men in the country.

A journalist goes undercover in Blackwell’s Island Insane Asylum.

An undercover federal agent behind a massive sting operation that took down dozens of gun-runners and drug-dealers tells all.

For the past 16 months, he had worked as a mole, posing as a militant jihadist in the Islamic State while passing critical information to a secret branch of Iraq’s national intelligence agency. His record was stunning: He had foiled 30 planned vehicle-bomb attacks and 18 suicide bombers, according to Abu Ali al-Basri, the agency’s director. Captain Sudani also gave the agency a direct line to some of the Islamic State’s senior commanders in Mosul.

When her son was sentenced to 25 years for Brooklyn’s 2003 “grid kid” slaying, Doreen Quinn Giuliano was sure he’d been wrongfully convicted. To prove it, she went undercover, testing her sanity, her marriage, and the justice system.

The documentary filmmakers from Longbow Productions said they wanted to tell the story of the Bundy Family and their standoff with the government. Their cameras were real, but the people behind them were undercover FBI agents.

He was the most powerful fish broker in New Bedford, America’s most valuable seafood port. The Russians who arrived looking to buy his operation were undercover agents and he told them everything.

Inside America’s resurgent paramilitary movement.

“Private prisons are shrouded in secrecy. I took a job as a guard to get inside—then things got crazy.”

A French reporter went undercover as potential “caliphette” and recieved a marriage proposal from a senior ISIS commander.

Going undercover with David Sullivan, cult infiltrator.

An undercover cop infiltrates a group of British activists, befriending and then betraying them.

The inner workings of a surprisingly amiable Holocaust denial conference.

A weekend at a Christian gay-to-straight sexual reorientation retreat.