The Girl Is Murder by Kathryn Miller Haines (2011)
Iris's world is complicated, trapped as she is between her posh uptown life, and her new downtown life, not quite fitting in either place anymore. She also walks a fine line between childhood and adulthood, wanting to help her father with his work because they need the money, but meeting his resistance at every turn because she is "just a child." Trying to fit in at her new school isn't easy either. The first people she meets are Pearl and Paul, a brother and sister who try to befriend her. Pearl is an outcast, especially vilified by the Rainbows, the tough-talking group that Iris befriends to try and track down their missing friend. The group takes Iris out to Harlem with them for drinking and dancing to a new kind of music that Iris has never heard before, but instantly loves. She finds herself lying to both sets of friends about different aspects of her life. Meanwhile, she's ignoring her old friend Grace from the upper east side because she feels like Grace is taking perverse joy in Iris's social descent.
Although marketed towards fans of Veronica Mars, this book reminded me more of Ten Cents a Dance by Christine Fletcher. Set in the same era, The Girl Is Murder included nice period details including contemporary slang expressions, tasty treats like egg creams (whatever those are), and featured boys in zoot suits, with a slight nod to the Zoot Suit Riots (which I always thought was just a song but was, in fact, an actual series of riots.)
The audio narrator was really fantastic, what with her New York accent and convincing dialogue. This was one of the better audio performances I've listened to, and I'm so glad I opted for this format. But I'm sure the book is great too, so however you like it you should give it a try!