The sequel to The Unexpected Enlightenment of Rachel Griffin. Lots of spoilers ahead.
Indeed it begins with the Agents' questioning students to find out what happened and what they were magically prevented from knowing. After their own questioning, our trio of Rachel, Natissia, and Siggy, with Lucky, spy because the Agents won't tell them anything. Even the Agents who admit that they are on the front line of the fighting.
Some horrific revelations ensue. One girl remembered that her parents -- or rather her aunt and uncle, raising her -- offered her as a human sacrifice. The person asking for the sacrifice rejected her because they didn't love her enough for it to be a sacrifice. And more.
Siggy acts erratically. Rachel does seem to take everything he says at face value, though knowing he's not very honest. He seems to be more in shock from his transition of the world of magic from the mundane than Rachel realizes.
Vladimir von Dread is not happy with the way the Knight of Walpurgis acquitted themselves under attack. Rachel sees more of Gaius, and also gets little help from her family, and gets to meet the title elf. More revelations about the world ensue. Meanwhile, the culprits move again. . . .
It includes a student who's unable to use a flying broom, which you don't need magic for, putting essences in elixirs because it's too dangerous to put them straight into human bodies, Rachel's reflecting that she doesn't want to be a queen, two young princes trying to get rid of the oldest, how no one knows the meaning of the words "saint" and "steeple", and much more.