At the request of his older sister, Hōtarō Oreki joins his high school's Classic Literature Club to stop it from being abolished. He meets Eru Chitanda in the club room, and after a short conversation he wonders why she was able to enter the room without a key, which he obtained earlier. They are interrupted by Satoshi Fukube, and as Hōtarō tries to leave he is stopped by Eru who wants to know how the room was locked in...