 On the request of the Reverend Mother to bring someone in to organize the library, the bishop sends the only qualified librarian available on staff, accident-prone Brother Paul Bernardi. And the Reverend Mother assigns Sister Bertrille to assist Brother Paul in her hope that "two wrongs will make a right". Among the accidents caused by Brother Paul are the burning of the bookshelves by his magnifying glass and creating a hole in the library wall while pulling out a nail. With the latter however, he and Sister Bertrille discover some old parchments inside the wall, the parchments which end up being the priceless San Tanco scrolls. In his absentmindedness, Brother Paul places the parchments on the pile of books that are to be discarded. In an effort to get new bookshelves, Sister Bertrille deals with "Swapping Salvador", new bookshelves for the old books that were to be discarded anyway. Salvador plans to grind the books into pulp, and with the old books are the parchments. When Brother Paul and Sister Bertrille discover the possible fate of the parchments, Sister Bertrille quickly flies to Salvador s just in time to save the parchments. The two wrongs eventually do make a right as the library comes together beautifully and Brother Paul is assigned to work at the Vatican library.