Theoretical physicist Paul Dirac (1902-84) was "the British Einstein," the youngest man to ever win the Nobel Prize for Physics, the gifted scientist who predicted the existence of antimatter, and a man so taciturn and strange that he seemed to reside in a separate universe. At times, his literal-minded rigidity could seem severe: He once scolded Niels Bohr, "I was taught at school never to start a sentence without knowing the end of it," and it is said that he cried only once in his life, the day Einstein died. Graham Fermelo's compassionate biography uses previously undiscovered family archives to rescue Dirac from facile caricature. He explores the origins of this seminal thinker's autistic behavior and explains how his remorseless pursuit of research ultimately rested on his absolute belief in the beauty of mathematics.