Kat, Incorrigible book 4. Very much a sequel to the trilogy, so spoilers for them ahead.
Kat is summoned away from the fitting for her gown -- she must have a Season -- to receive a task as a Guardian: to deal with an illusionist and thief who worked at Society events. Three young men are also on the task, and one is Alexander.
It concerns an old friend with a new name, making jewels look different, questions of fatherhood, and more.