The Wyndham case - Jill Paton Walsh

The locked library of St Agatha's College, Cambridge houses an unrivalled, and according to certain scholars, deeply uninteresting collection of seventeenth century volumes.

It also contains one dead student.

Tragic and accidental, of course, even if malicious gossip hints that Philip Skellow had been engaged in stealing books rather than acquiring knowledge when he'd slipped, banged his head, and bled to death overnight.

Only Imogen Quy, the college nurse, has her doubts - until another student is found, drowned in an ornamental fountain...