New York City, 1939: At the height of the Great Depression, a time when President Roosevelt is trying to keep America out of World War II, Giddy Brodsky is lucky to have a job as a cigarette girl at a Manhattan jazz club. Nevertheless, she dreams of establishing a cosmetics business and leaving the poverty-stricken Lower East Side tenements behind. She has lived there with her family ever since they fled Russia, forced to emigrate after a group of Cossacks burned down their village, and her memories continue to haunt her.

Giddy tries to focus on the future until, during an evening streetcar ride, she thinks she recognizes one of the Cossacks who changed her life forever. Determined to get answers, she enlists the help of Carter van der Zalm, the Chief Commissioner of Immigration at Ellis Island, who is hunting the same man. He suspects the Russian is involved in an assassination plot that will destroy American and Soviet relations, and he enlists Giddy to moonlight as a spy for him. But when she finally tracks down the man they're both seeking, she finds herself in the middle of a shocking political conspiracy that changes everything she once held true.

In the tradition of Lara Prescott's The Secrets We Kept and Kate Quinn's The Rose Code, The Jazz Club Spy is a glittering and gritty look at pre-WWII America, and the personal battle one woman wages between justice and forgiveness.