On a mid-December afternoon in 2020, I drove to a trailhead at Redwood Regional Park in the Oakland Hills. It was a temperate day, but Frances Haugen emerged from her car wearing a heavy parka, fleece, gloves, leggings, and ankle warmers. As joggers passed by in shorts, Haugen told me the story of her nerve damage. Even a slight chill still meant hours of excruciating pain.

She had spent the last several months taking notes about her misgivings, as she grew more certain that Facebook wasn’t committed to integrity work. Whenever something bothered her or felt significant, she wrote it down. She didn’t know what she was going to do with this material. She had reached out to a tech advocacy non-profit organisation, but her contact there told her it wasn’t in the business of whistleblowing. That Saturday afternoon, we walked for a few minutes, the trail a little too heavily tracked by joggers and mountain bikers, before pulling into a clearing to have a real chat.