The Ruby in the Smoke (Sally Lockhart, #1)

Sally Lockhart's father was an unconventional man who preferred to teach his daughter how to run a business and shoot straight from a pistol, rather than school her in the social graces expected of a young lady. When he dies suddenly and unexpectedly, on a voyage to the Far East, Sally receives a mysterious letter containing a strange warning - one that is to lead to yet another unexpected death. Soon Sally finds herself at the heart of a deep and dangerous mystery, and one which she is determined to solve at all costs.