Queenpin by Megan Abbott

By the author of Dare Me and The End of Everything

A young woman hired to keep the books at a down-at-the-heels nightclub is taken under the wing of the infamous Gloria Denton, a mob luminary who reigned during the Golden Era of Bugsy Siegel and Lucky Luciano. Notoriously cunning and ruthless, Gloria shows her eager young protégée the ropes, ushering her into a glittering demimonde of late-night casinos, racetracks, betting parlors, inside heists, and big, big money. Suddenly, the world is at her feet—as long as she doesn't take any chances, like falling for the wrong guy. As the roulette wheel turns, both mentor and protégée scramble to stay one step ahead of their bosses and each other.