GOSICK takes place in 1924 in a small, made-up European country of Sauville. The story centers on Kazuya Kujo, the third son of a Japanese Imperial soldier, who is a transfer student to St. Marguerite Academy, where urban legends and horror stories are all the rage. There he meets Victorique, a mysterious yet beautiful and brilliant girl who never comes to class and spends her days reading the entire content of the library or solving mysteries that even detectives can't solve.
In a world where dead people turn into books and are stored in the Bantorra Library where anyone who reads a book can learn their past. Bantorra Library is maintained by Armed Librarians who wield psychic powers and their enemy is a religious society known as Sindeki Kyōdan.