Close to the end of Easter term, 1358, the colleges of the University of Cambridge are at war over the creation of a Common Library. Scholars from the poorer hostels are delighted by the scheme, but others see it as a dangerous precedent, and demand that the project be abandoned. At the meeting of all the masters to discuss the matter, a book flies through the air striking one of their number and leaving him seriously wounded. Matthew Bartholomew is called upon for his skills as a physician, but his experience is even more in demand when a body is found floating in the pond of the library's garden on the eve of its openining.