Sorcery and Cecelia or The Enchanted Chocolate Pot - Patricia C. Wrede

A great deal is happening in London and the country this season.

For starters, there's the witch who tried to poison Kate at the Royal College of Wizards. There's also the man who seems to be spying on Cecelia. (Though he's not doing a very good job of it--so just what are his intentions?) And then there's Oliver. Ever since he was turned into a tree, he hasn't bothered to tell anyone where he is.

Clearly, magic is a deadly and dangerous business. And the girls might be in fear for their lives . . . if only they weren't having so much fun!