What starts with a mysterious gun in an airport bathroom and a fake refugee identity opens the door to a nationwide network of far-right extremists inside Germany’s military and police. It’s a story about a changing national identity — and the backlash against it — raising a question that democracies across the world are waking up to: What happens when the threat is coming from within?

See all episodes of Day X at nytimes.com/dayx

Unlock full access to New York Times podcasts and explore everything from politics to pop culture. Subscribe today at nytimes.com/podcasts or on Apple Podcasts and Spotify.