Pretty Baby by Mary Kubica. Kubica lives outside Chicago. the cover says her last book, The Good Girl, was a bestseller. Woman impulsively brings home a homeless teen and the girl's infant. Family are not happy and the teen starts to do weird stuff. Or something. The dust cover says, "as clues into Willow's past begin to surface , Heidi is forced to decide how far she's willing to go to help a stranger."
Kubica wore a kind of dark turquoise cardigan sweater for her author photo. At least I think it's a sweater, it might be a jacket. Fake Library Stats always makes cardigan jokes. And cat jokes. And drinking jokes. There is not a lot of variety on Fake Library Stats.