Something mysterious has been going down in New Jersey this week…but it’s NOT drones. It’s that thousands of people are looking at airplanes in the night sky and thinking they see UFOs. What causes mass delusions like this wave of now mostly debunked drone sightings? In this concluding episode of How We Got Here, Max and Erin share four stories of famous mass hysterias and talk to William Bernstein, an author who writes about the science of mass delusions and why they happen.