Fingersmith by Sarah Waters
This was one of the most well written, well-constructed stories I've ever read. Slow building but packing quite a punch with a complex plot neatly and intricately woven. Waters' attention to detail regarding the characters and their surroundings was superb. The skill with which she fleshed out this story is extraordinary - this is clearly a writer with immense talent. It was wonderful - gripping, touching, just perfect.