Taken to the Grave by Cara Devlin

The Bow Street Duchess Mystery series comes to a thrilling conclusion in the seventh and final book, Taken to the Grave.

As Audrey Sinclair reaches the end of her mourning period, she and Hugh Marsden, the Viscount Neatham, are at long last looking toward their future together — and hoping for a respite from the dangerous criminal investigations they’ve found themselves entrenched in.
However, when the niece of Bow Street’s chief magistrate Sir Gabriel Poston goes missing, and Audrey and Hugh link her disappearance to a stirring public panic over suspicious deaths at the Vauxhall Pleasure Gardens, they agree to one final inquiry…