After World War II, when a new German democracy was born in the western region of the vanquished Third Reich, tens of thousands of civil servants were hired to work for newly formed government agencies to get the new republic quickly on its feet. But there was an enormous flaw in the plan: no serious vetting system was put in place to keep war criminals out of government positions. Ex-Nazis--people who had been involved in mass murder, drafting antisemitic laws, and the persecution of Hitler's opponents, as well as other depravities--resumed their careers without consequence in the newly created Federal Republic of Germany. Former Nazis who had established an early foothold in postwar government agencies helped each other get government work by writing letters of recommendation called Persilscheine. These "Persil Certificates," named after a popular detergent, made an ex-Nazi's recorded past just as clean as fresh laundry, and a whole generation of German government officials with Nazi pasts was never brought to account. Ex-Nazis were given preference for government jobs even over victims of Nazi policies and anti-Hitler resisters. They swapped Nazi uniforms for suits, Hitler salutes for handshakes. And with help from the highest levels of West German government and even the CIA, they swept their crimes under the carpet and resurrected their careers. Nazis at the Watercooler illuminates the network of ex-Third Reich loyalists and the U.S. government's complicity that enabled this mass impunity.