Oreki Hotaro is minimalistic high school boy. One day, he joins the Classic Literature Club at his elder sister's request.
There he meets Chitanda Eru, Fukube Satoshi, and Ibara Mayaka. Chitanda is a calm beautiful girl but she turns into an embodiment of curiosity once she says, "I'm interested in it (Watashi, Kininarimasu)". Fukube is a smiling boy with a fantastic memory who calls himself a database. Ibara is a short girl and is strict with others and herself. She loves Fukube, but he always dodges her approaches.
They begin to investigate a case that occurred 33 years ago. Hints of the mystery are buried in an old collection of works of the former members of Classics Club. The collection is titled "Hyouka."