The book as usual is about the Bristow family and their relatives. This book starts in pre World War I London and continues into the beginnings of the post-war period. While Fiona and Joe Bristow are always the cornerstones of the story, this installment was mostly about the relationship between Willa Alden and Seamus Finnegan and their conflicted love story. In the previous book the two had climbed Kilimanjaro together and Willa fell and broke her leg on the way down. By the time Seamus got her to a hospital her leg was so gangrenous the doctor recommended amputation and Seamus told him to go ahead despite Willa's protests. She hated him for it. Despite that hate they still both love each other and have a hard time having any real relationships with other people because they are always pining for each other. Willa flees London and conflict as she always does, which takes her on further adventures around the world. Seamus tries to find love elsewhere but has trouble as well.
Along with all of this there are subplots that have to do with the war, including a complex spy ring.
Altogether an enthralling book which I enjoyed as much as the first two. I wasn't able to finish it inflight, but I finished it within a week. The book does a good job of tying up the loose ends in a satisfying way. Sometimes very much what you would expect, and other times not.
It's hard to summarize a book of this scope so I'll just say if you enjoy a good epic story of historical fiction, check out the Rose trilogy by Jennifer Donnelly. You won't be disappointed. I purposely took my time between each book as I wanted to keep the journey going with these characters as long as I could. Honestly, I'm going to miss some of them.