In the glittering intellectual world of 1920s Paris expatriates, Pauline Pfeiffer, a writer for Vogue, met Ernest Hemingway and his wife Hadley in a circle of friends that included Gertrude Stein, F. Scott Fitzgerald, John Dos Passos, and Dorothy Parker.

Pauline forged a strong bond with Hemingway, and in 1927, shortly after his divorce from Hadley, she became his second wife. Pauline also became her husband's devoted editor, and her wealthy family provided moral and financial support, even converting a barn at the family home in Piggott, Arkansas into a dedicated writing studio, where much of his 1929 novel A Farewell to Arms was written. The thirteen years the two were married were some of Hemingway's most productive.

The marriage eventually ended in the way it began: with an affair. Hemingway left Pauline for Martha Gellhorn, the third of his four wives, in 1940. Unbelievable Happiness and Final Sorrow is the story of the Hemingway-Pfeiffer marriage, a narrative of Pauline Pfeiffer's fascinating life and her influence on one of America's most enigmatic literary icons.