Henry Wilkens burst through the doors of the emergency room covered in his wife's blood. But was he a grieving husband, or a ruthless killer who'd conspired with bandits to have her murdered? To find out, the San Francisco police turned to technology, and a new machine that had just been invented in Berkeley by a rookie detective, a visionary police chief, and a teenage magician with a showman's touch. John Larson, Gus Vollmer and Leonarde Keeler hoped the lie detector would make the justice system fairer - but the flawed device soon grew too powerful for them to control. Tremors in the Blood reveals the incredible truth behind the creation of the polygraph, through gripping true crime cases featuring explosive gunfights, shocking twists and high-stakes courtroom drama.