After reaching about 70% I’ve just read the chapter where Dr Watson is taken by a sinister man with a gun (Underwood) to meet another man in a large mansion.
This man won’t give his name but is clearly on a par with Sherlock Holmes intellectually. He says he is a mathematician. Does this not tell Watson that the man is in fact Moriarty?
Anyway Moriarty claims he doesn’t like the House of Silk (SILC?) and so is going to help Holmes. Very suspicious that.