Joel is fascinated by the magical art of Rithmatics, but unfortunately only a chosen few have the necessary gift and Joel is not one of them. Undaunted, Joel persuades Professor Fitch to teach him Rithmatic theory — and soon finds that his knowledge is put to the test when someone starts murdering the top Rithmatic students at his school. But can Joel work out the identity of the killer and stop them before they realize just what a threat Joel actually is?