A mysterious letter detailing a supposed Islamist plot to take over schools shocked Britain in 2014. But who wrote it? From Serial Productions and The New York Times, “The Trojan Horse Affair,” an investigation that became bigger than we ever imagined. All eight parts are available now, wherever you get your podcasts.

“If you keep your mouth shut, you’ll be surprised what you can learn.”

“Has anybody called you?”

“Tedious and brief.”

“If anybody could find it, it would be me.”