Hodgkin, M.R. Student Body (New York: Scribner's, 1949) 226 p.
Caradoc College is stunned when a student falls to his death from a railroad trestle. There's mysterious work afoot in the library as well. Someone has been writing incriminating notes in the margins of library books. Blackmail notes in various well-known handwriting are turning up in library carrel drawers. The librarian is Miss P. Cecily, known to all as Cecily Parsley. "She was a forbidding, book-mad spinster ..." but alas a very minor character in this story. There is a suspenseful scene in the darkened stacks on p. 172: "But if I were the murderer--"
He took another step forward, and as he did so one of the fire doors far away in the distance opened, a loud cheerful assistant's voice roared a perfunctory "Everyone out?" and with a click of the master switch all the lights in the stacks went out.