Grudge Match by Mike Lupica

 I discovered that I had missed a bunch of the Sunny Randall novels, so I've been trying to catch up.

In Grudge Match, Sunny is hired by mobster Tony Marcus to find a girl who ran a lot of his operations and with whom he was supposedly in love. She has disappeared and Sunny wants to find out why. Then she learns that Marcus's main rival, Gabriel Jabari, is also looking for the girl. And someone is following Sunny and even breaks into her home. She's finding this a very frustrating case to solve.

At the same time, Sunny's trying to deal with her boyfriend Richie unexpectedly finding himself in charge of his young son, who had been living in London with Richie's ex-wife. Likeable characters, good story.