Bright Young Things by Anna Godbersen
It's 1929 and Letty Larkspur and Cordelia Grey have escaped their small Midwestern town to chase big dreams and even bigger secrets. Amongst the glittering metropolis of New York City, they meet Astrid Donal, a flapper who has everything she could ever want, except for the one thing Letty and Cordelia have to offer-true friendship. Set in the dizzying summer before the market crash, against the vast lawns of the glamorous Long Island mansions and on the blindingly lit stages of Broadway, three girls will find scandal, intrigue, and romance.