Tells the story of the Finnish-American mathematician Lars Ahlfors (1907-1996). He was educated at the University of Helsinki as a student of Ernst Lindelof and Rolf Nevanlinna and later became a professor there. He left Finland permanently in 1944 and was professor and emeritus at Harvard University for more than fifty years. At the age of twenty-one Ahlfors became a well-known mathematician having solved Denjoy's conjecture, and in 1936 he established his world renown when he was awarded the Fields Medal, the "Nobel Prize in mathematics". In this book the description of his mathematics avoids technical details and concentrates on his contributions to the general development of complex analysis. Besides mathematics there is also a lot to tell about Ahlfors. World War II marked his life, and he was a colorful personality, with many interesting stories about him. Olli Lehto, the author of the book, first met Lars Ahlfors and his family as a young doctor at Harvard in 1950. Numerous meetings after that in various parts of the world led to a close friendship between them.