Code Name Sapphire by Pam Jenoff

"A heart-wrenching exploration of the decisions women must make when their loyalties are put to the test in the most unimaginable of circumstances." –Sarah Penner, New York Times bestselling author of The Lost Apothecary
A woman must rescue her cousin's family from a train bound for Auschwitz in this riveting tale of bravery and resistance, from the bestselling author of The Lost Girls of Paris
1942. Hannah Martel has narrowly escaped Nazi Germany after her fiancé was killed in a pogrom. When her ship bound for America is turned away at port, she has nowhere to go but to her cousin Lily, who lives with her family in Brussels. Fearful for her life, Hannah is desperate to get out of occupied Europe. But with no safe way to leave, she must return to the dangerous underground work she thought she had left behind.
Seeking help, Hannah joins the Sapphire Line, a secret resistance network led by a mysterious woman named...