I truly enjoyed Gabaldon's early novels in the Outlander series, but felt she ran out of steam in the last two. This is a novel about one of her minor, but significant characters - Major Lord John Grey - a closeted gay aristocratic officer in His Majesty's Army. The story is a murder mystery/spy thriller that allows Lord John to plumb the various parallel worlds in London from the "Molly walks" where male prostitutes strut their wares to elegant aristocratic music soirees. The story is fun as Gabaldon uses a breakneck pace and tons of details (you can really smell London in June) to pull us in. This book is a fun read.