In the spell-powered city of Tarreton, the wealthy have all the magic they desire while the working class can barely afford a simple spell to heat their homes. Twelve-year-old Isaveth is poor, but shes also brave, loyal, and zealous in the pursuit of justicewhich is lucky, because her father has just been wrongfully arrested for murder.

Isaveth is determined to prove his innocence. Quiz, the eccentric eyepatch-wearing street boy who befriends her, swears he cant resist a good mystery. Together they set out to solve the magical murder of one of Tarretons most influential citizens and save Isaveths beloved Papa from execution.

But each clue is more perplexing than the next. Was the victim truly killed by Common Magicthe kind of crude, cheap spell that only an unschooled magician would useor was his death merely arranged to appear that way? And is Quiz truly helping her out of friendship, or does he have hidden motives of his own? Isaveth must figure out who she can trust if shes to have any hope of proving her Papas innocence in time. . .