The FBI has always kept tabs on political activists. During the directorship of J. Edgar Hoover, it was a Bureau-wide obsession. Did you see that guy who didn’t quite look like a journalist, taking pictures at a demonstration? He was probably FBI. Did you say something mildly subversive in a radio interview? It went in your file. Did you attend a meeting of a left-leaning organization? The attendee who didn’t contribute but took copious notes was possibly an informant. This third volume of selected FBI files liberated by MuckRock documents the FBI’s pursuit of activists and dissenters ranging from Margaret Sanger to Malcolm X. Despite the absence of evidence, Hoover suspected Communist influence in every political protest. He grilled Martin Luther King, Jr., about Communist sympathizers in the civil rights movement (while offering reporters off-the-record hints about King’s extramarital affairs). The Bureau investigated the supposed threat posed by Cesar Chavez and the United Farm Workers but not threats to them, even after the detonation of a bomb in their office. The Bureau persevered: files on Holocaust survivor Hedy Epstein cover six decades, from unfounded rumors of Communist connections to her participation in a Black Lives Matter demonstration. Recently, we hoped against hope that a former FBI director would save us from our current political predicament. These documents remind us of the FBI’s troubling history.