The Vault -- Peter Lovesey

While The Circle reminded me of Agatha Christie's books, The Vault was more like one of Reginald Hill's police procedurals.  It even has those same brief (so brief that they're easy to miss if you're reading too fast, so slow down, dammit) moments of hilarity:

He gave Wigfull a speculative glance.  "You can pick up some useful things quite cheaply.  The Victorians made special mugs for people with large moustaches.  There was a trough across the top to keep the whiskers from getting soggy.  Worth looking out for."

Wigfull's brown eyes about the great frizz were a study in hostility.

Anyway.  A skeletal hand encased in cement delivered to the police department in a pizza box, Mary Shelley's personal writing table, a missing American, a series of watercolors depicting Frankenstein that may be a newly discovered William Blake series, a pushy member of the press and, of course, murder. 

Pretty rad -- not quite totally rad because I had most of the mystery figured out rather early on, but fun enough that I want to go back and read the Peter Diamond series from the beginning.