The Sign of the Four
Other thoughts/reviews: Shelf Love: http://shelflove.wordpress.com/2012/05/28/the-sign-of-four-review/
live through books: http://livethroughbooks.wordpress.com/2012/06/20/blast-from-the-past-the-sign-of-the-four/
The Guardian: http://www.guardian.co.uk/books/2012/jun/26/review-sign-of-four-conan-doyle