The Rithmatist by Brandon Sanderson
A killer is on the loose...Joel is fascinated by the art of Rithmatics - with its lines of power and ability to bring chalk drawings to life - but only a few have the gift and he is not one of them. When Rithmatic students from Joel's school start disappearing, he is keen to investigate. Since he's not a Rithmatist, Joel seems to be safe - but others are dying. Can he find the killer before the killer realizes just what a threat Joel really is?