Kirigamine Ryo ia a high-school student who develops a great passion for baseball and mysteries; so much so that she even joins her school's Detective Club. She may be more eager than skilled, but even so, there doesn't seem to be many cases around for her to solve. So when a minor case does pop up, Ryo quickly takes it on. Dragging along her less-than-willing Biology teacher, Ishizawa, as backup, Ryo is ready to tackle even the most bizarre cases after school!