Every evening, when the library closes, the Guardians come out of their hiding places to take care of the books. You meet Ratmini on his first day of work. He asks for your help in creating the Ratmembert, a mythical delicacy that will be shared at the end of the night by all the secret inhabitants of the library. You have to visit all the keepers (find all the clues and scan them) to get the cheese needed for the feast.