This is episode four of Swimming with Shadows: A Radiolab Week of Sharks. Alison Kock was working at a car wash in Cape Town when she made a discovery that completely changed the course of her life. Inside a customer’s trunk, she found photographs of white sharks flying so high above the water they looked like airplanes. She followed those photographs to False Bay, “the Great White Capital of the World.” These sharks, in this place, are the apex of apex predators. Or they were. Until they mysteriously began to disappear. Special thanks to Kathry...