Author: Arthur Conan Doyle
The Sign of the Four is the second Sherlock Holmes novel, first serialized in Lippincott's Monthly Magazine. It's a complicated plot, winding its way across India and through the streets of London. But at its heart, it's a hunt for stolen treasure.
Some important elements are added to the franchise in this second installment. Right off the bat, we learn of Holmes's drug use, both cocaine and heroin. We also meet Mary Morstan, Watson's future wife. It is, in fact, Mary's treasure (sort of) that they're after.
Once again, there's a long segue - India this time rather than Utah. Once again, I would say the segue is the weakness of the book. The racism and colonialism of 19th century England are on full display. Fortunately, it's not five chapters long this time.
Overall, I would say The Sign of the Four is not as strong as A Study in Scarlet - too much exposition, not enough detective razzle-dazzle.