Borrower of the Night by Elizabeth Peters

Vicki Bliss is a historian who has just had the find of a lifetime fall into her lap, proof that a shrine built by Remenschneider (I listened to the book so spelling may be suspect) actually existed. A race between herself and her lover, Tony Lawrence, as well as treasure hunter George Nolan, takes them all to Germany in an old, supposedly haunted castle.
In the setting of the book, the castle is now a hotel run by the final countess (who married into the family) and the last surviving Drachenstein, Irma. The Grauphin, the old countess, is an iron-fisted besom while her niece is a “perfect heroine” including to the point of being a fainting flower. There is also at the castle a Doctor Blankenhagen who may or may not also be looking for the shrine. The countess also has a séance-loving friend and there is an older gentleman, Schmidt, who round out the party.
Peters infused the book with a sense of humor about the whole gothic atmosphere, at one point, Vicki says something along the lines of, “A secret passage? That was all we needed.” Love those bits of self-awareness.

Four stars

Follows The Camelot Caper

Followed by Street of the Five Moons

This book came out in 1973

Borrowed as an ebook from CloudLibrary

Opinions are my own