Hōtarō Oreki doesn't like to do things that he considers a waste of energy, but his older sister asks him to join the Classic Literature Club in high school. Another student, Eru Chitanda, also joins and he is strangely unable to refuse or escape from Eru's passionate gaze of curiosity. Together with his friends, they discuss a variety of mysteries in school that only Hōtarō seems to be able to solve.