Winter of the World (The Century Trilogy, Book 2) by Ken Follett
Carla von Ulrich, born of German and English parents, finds her life engulfed by the Nazi tide until daring to commit a deed of great courage and heartbreak . . . . American brothers Woody and Chuck Dewar, each with a secret, take separate paths to momentous events, one in Washington, the other in the bloody jungles of the Pacific . . . . English student Lloyd Williams discovers in the crucible of the Spanish Civil War that he must fight Communism just as hard as Fascism . . . . Daisy Peshkov, a driven social climber, cares only for popularity and the fast set until war transforms her life, while her cousin Volodya carves out a position in Soviet intelligence that will affect not only this war but also the war to come.