This story began with a mysterious gun in an airport bathroom and led to a German military officer facing trial on terrorism charges. It’s a story about national identity and reckoning, mirroring the story of Germany itself. And years later, it’s still unfolding — 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 Subscribe today at nytimes.com/podcasts or on Apple Podcasts and Spotify. You can also subscribe via your favorite podcast app here https://www.nytimes.com/activate-access/audio?source=podcatcher. For more podcasts and narrated articles, download The New York Times app at nytimes.com/app.