The late scholar : the new Lord Peter Wimsey/Harriet Vane mystery / Jill Paton Walsh.

Enhanced descriptions from Syndetics:

When a dispute among the Fellows of St. Severin's College, Oxford University, reaches a stalemate, Lord Peter Wimsey discovers that as the Duke of Denver he is "the Visitor"--charged with the task of resolving the issue. It is time for Lord Peter and his detective novelist wife, Harriet, to revisit their beloved Oxford, where their long and literate courtship finally culminated in their engagement and marriage.

At first, the dispute seems a simple difference of opinion about a valuable manuscript that some of the Fellows regard as nothing but an insurance liability, which should be sold to finance a speculative purchase of land. The voting is evenly balanced. The Warden would normally cast the deciding vote, but he has disappeared. And when several of the Fellows unexpectedly die as well, Lord Peter and Harriet set off on an investigation to uncover what is really going on at St. Severin's.

With this return in The Late Scholar to the Oxford of Gaudy Night, which many readers regard as their favorite of Sayers's original series, Jill Paton Walsh at once revives the wit and brilliant plotting of the Golden Age of detective fiction.