Life as a working-class girl in Prohibition-era New York isn’t safe or easy. But Vivian Kelly has a new job at the Nightingale, an underground speakeasy. Things are finally looking up for her and her sister, Florence...until the night Vivian learns that her friend Bea's uncle, a bouncer at the Nightingale, has died. His death is ruled a suicide, but Bea isn’t so convinced. She knew her uncle was keeping a secret: a payoff from a mob boss that was going to take him out of the tenements and into a better life. Now, the money is missing. Vivian and Bea uncover more than they expected when rumors surface of a mysterious letter writer who's blackmailing Vivian's poorest neighbors for their most valuable possessions, threatening poison if they don't comply.

Prohibition is a dangerous time to be a working-class woman in New York City, but Vivian Kelly has finally found some measure of stability and freedom. By day, she’s a respectable shop assistant, delivering luxurious dresses to the city’s wealthy and elite. At night, she joins the madcap revelry of New York’s underworld, serving illegal drinks and dancing into the morning at a secretive, back-alley speakeasy known as the Nightingale. She's found, if not love, then something like it with her bootlegger sweetheart, Leo, even if she can't quite forget the allure of the Nightingale's sultry owner, Honor Huxley. Then the husband of a wealthy client is discovered dead in his study, and Vivian was the last known person to see him alive. With the police and the press both eager to name a culprit in the high-profile case, she finds herself the primary murder suspect.

New York, 1924. Vivian Kelly's days are filled with drudgery, from the tenement lodging she shares with her sister to the dress shop where she sews for hours every day. But at night, she escapes to The Nightingale, an underground dance hall where illegal liquor flows and the band plays the Charleston with reckless excitement. With a bartender willing to slip her a free glass of champagne and friends who know the owner, Vivian can lose herself in the music. But then she discovers a body behind the club. With too many people assuming she knows more about the crime than she does, Vivian finds herself caught between the dangers of New York's underground and the world of the city's wealthy and careless.