Cloak Mage book 4
The continuing adventures of Nadia. Opens with a scene where she is working with the Shadowhunters to hunt down a summoner, in Florida. But with that wrapped up, Riordan gets another call. A trip to England. And since she's free she can come -- except that just then, she gets a call from the High Queen. They are both on their own.
And she's on a caper, with directions to steal something so that its owner doesn't know it's stolen. It involves two characters she's met before, questions of sugar smuggling, multiple plans, learning more about the Singularity, and more.