For decades now, America’s national security state has grown ever bigger, ever more secretive and powerful, and ever more abusive. Only once did someone manage to put a stop to any of it. Senator Frank Church of Idaho was an unlikely hero. He led congressional opposition to the Vietnam War and had become a scathing, radical critic of what he saw as American imperialism around the world. But he was still politically ambitious, privately yearning...

"Vivian Gordon went out before midnight in a velvet dress and mink coat. Her body turned up the next morning in a desolate Bronx park, a dirty clothesline wrapped around her neck. At her stylish Manhattan apartment, detectives discovered notebooks full of names--businessmen, socialites, gangsters. And something else: a letter from an anti-corruption commission established by Governor Franklin Delano Roosevelt. Led by the imperious Judge Samuel Seabury,...