Like almost everyone I meet over the coming three days, Foertsch switched to flat Earth ideology as a result of clicking on a YouTube video. That clip led to another, and before long, he was a believer. Early in his conversion, Foertsch came to Flat Earth Clues, a 14-part series by Mark Sargent, a baby-faced man from South Whidbey Island, Washington, whom those outside the movement might know as the star of the 2018 documentary Behind the Curve. The videos in Flat Earth Clues, which together have amassed more than 2 million views, feature Hollywood movie stills, meme-worthy images, and a calm but unsettling narration. The series hinges on simple questions. Why are most of the photos of the Earth from space composites? Why is it so difficult to find a nonstop flight between two cities in the Southern Hemisphere? Why do the major nations of the world seem content to share control of Antarctica? (Many flat-Earthers hypothesize that the North Pole is at the center of a flat disc, with the continents fanning out around it, and Antarctica forming the disc's icy circumference.) Sargent's approach sometimes seems reasonable. He mostly avoids other conspiracy theories. Religion comes up only in episode 10. At the end of each episode, he includes his email address and telephone number, along with the line: "Do your own research. And ask questions."