The Alice Network by Kate Quinn

I found this book really gripping - and found out at the end in the Author's Note that several of the characters were based on real people which made the story all the more interesting.

In 1947 Charlie St. Clair is an unmarried 19 year old American girl en route to Switzerland with her mother to receive an illegal abortion.  Her upper class parents have convinced her she is a whore who must take care of the "Little Problem".  But Charlie has other ideas.  Reeling from the suicide of her brother after his wartime experiences she is desperate to find her French cousin, Rose, who was her best friend in childhood but who nobody has heard from since 1943.

Charlie breaks away from her mother in Southampton and finds herself on the doorstep of Eve Gardiner who is the last government employee who wrote a report about the search for Rose when she was reported missing.  Eve is an angry old drunk with misshapen hands who greets Charlie with a loaded gun.  After Charlie pleads her case she allows her to stay on her sofa provided she is gone by the morning.  Charlie falls asleep and is awakened by Finn, a Scottish ex-con, ex-soldier who is now working as Eve's "hands" since she cannot do a lot with her own.  Finn convinces Charlie to stay with promises Eve will not even remember her threats from the prior night.  She does, and shares her story with Finn too.

Eventually the unlikely trio set out to France to find Rose.  In alternating chapters we go back to the first world war where we discover that Eve was in fact a British spy posted in France - part of the Alice Network.  The Alice Network was named for its leader who was code named Alice (but went by Lili) and became one of Eve's best friends.  While Eve is entirely fictional, Alice and the Alice Network actually existed in World War I, becoming one of the most successful spy networks of that war.

Through these alternating chapters we hear of Eve's horrific story and how she went from being a spy to an angry drunk.  We also learn why she has an ulterior motive in joining Charlie's search for Rose - she has her own search to conduct in order to deal with some demons from her past.  Finn also struggles with PTSD from his wartime experiences.  As such, the trio bond and become close despite their immense differences.

In the end we learn with Charlie what has happened to Rose and we hear the end of Eve's wartime story.  Though all the characters are damaged, they are likeable and therefore I found their version of a happy ending quite satisfying.