The Last Drop of Hemlock (The Nightingale Mysteries, Bk. 2)

The rumor went through the Nightingale like a flood, quietly rising, whispers hovering on lips in pockets of silence.
 
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 where the jazz is hot and the employees look out for each other in a world that doesn’t care about them. 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.

Though her better judgment tells her to stay out of it, Vivian agrees to help Bea find the truth about her uncle's death. But they uncover more than they expected when rumors surface of a mysterious letter writer, blackmailing Vivian's poorest neighbors for their most valuable possessions, threatening poison if they don't comply.

Death is always a heartbeat away in Jazz Age New York, where mob bosses rule the back alleys and cops take bootleggers’ hush money. But whoever is targeting Vivian’s poor and unprotected neighbors is playing a different game. With the Nightingale's dangerously lovely owner, Honor, worried for her employees' safety and Bea determined to discover who is responsible for her uncle's death, Vivian once again finds herself digging through a dead man's past in hopes of stopping a killer.