I enjoyed this one a lot.
Nicholas Valiarde's adoptive father was framed and executed for the crime of necromancy. Now Nicholas is involved in a complex web of plots to have the nobleman who engineered this convicted of a capital crime he didn't commit (as oppposed to the many he did). In the course of one part of his plans, he crosses paths with the mysterious Doctor Octave, which is when things get really complicated....
Set in the fictional world of Ile-Rien, this is a sort of fantasy version of Victorian London with a Holmes-esque flavour and a generous dose of magic added. The plot is satisfyingly complex, the fictional world is wonderfully well constructed and the characters are sympathetic and believable. This book would make a brilliant film, if only they didn't mess it up.
There appears to be an entire trilogy set in the same world, so I shall be hunting that down as soon as I can.