The Apsley House Incident (Rannoch Fraser Mysteries, #14.5 )

A Rannoch Fraser Mysteries novella October 1820. As London simmers over the scandalous royal divorce trial, a pistol shot aimed at the Duke of Wellington's carriage shatters the peace of the autumn night. When Malcolm and Mélanie Rannoch learn their friend Robby Simcox has been arrested for the crime, they are convinced it is a miscarriage of justice, but it will require all their resources as former spies to uncover the truth. The race against time to save Robby from the gallows takes the Rannochs across the breadth of London, from the slums of St. Giles to elegant Mayfair to lively Covent Garden, and to Wellington's glittering home at Apsley House. But the culprit proves cleverly elusive. The consequences of their investigation could rip Robby's sister Bet from her aristocratic true love–and may also reveal secrets that threaten all Malcolm and Mélanie hold dear...