It's a mystery. It's also a mystery as to how it stopped being one. After searching the internet for quite a while, I fear it will remain an unsolved one, unlike the mystery in the book. I think for many readers, we're enchanted with this take on the Sherlock mythos, then betrayed by our own enjoyment of it. Every interview with the author I can locate finds him both mentioning it as a mystery, followed by his comments only as a family drama of sorts. It's still a good book. It's still well-written. But the author is guilty of the crime of making us want something, then giving us something entirely different. Perhaps the mystery of the missing mystery is a mystery even to him.I think that I, like many readers, are left with only our unfulfilled desires of what kind of mystery it could have been. Would that have been a better book? It's a mystery.