The first biography in English of a leading Dutch American physicist, who discovered the subatomic property of "spin" and spearheaded the search for Hitler's atom bomb as World War II came to an end. This engaging biography of an important Dutch physicist brings to light his significant scientific contributions and remarkable life story. Based on recently released archives and material from Goudsmit's daughter Esther, science journalist Martijn van Calmthout has reconstructed a life marked by both brilliance and tragedy. As a young man Sam Goudsmit came to international attention when he and a colleague published a seminal paper that introduced the property of electron spin into atomic theory. This discovery helped to remove remaining questions about atomic theory and brought him into contact with the likes of Einstein, Heisenberg, and other leading physicists of the early 20th century. In 1927, he was offered a position at the University of Michigan and moved with his wife to the United States. When the Nazis invaded the Netherlands, Goudsmit, a Jew, feared for the lives of his parents and other family members still in Holland. His attempts to get his German colleague Werner Heisenberg to intervene on their behalf proved fruitless. Toward the end of World War II, he was recruited by the Department of Defense as the scientific leader of the co-called Alsos mission, whose task was to search for evidence of German atom-bomb development. The team eventually found stores of uranium ore and a nuclear reactor, among other evidence. While in Europe, Goudsmit had an opportunity to return to The Hague, his hometown. There in the rubble of his parent's house, he discovered that they had been deported to Auschwitz. After the war, he returned to the United States and became the editor of Physical Review and Physical Review Letters; the latter is a leading physics journal to this day. But guilt over his failure to save his parents haunted him for the rest of his life. This is a biography that in part reads like a thriller and restores long-overdue recognition to an important 20th-century physicist.