De vallei der verschrikking (De complete avonturen van Sherlock Holmes # 4)

The book shifts between detective work and a secret society's story, which kept me hooked. I wonder what inspired the choice to tell it this way — was it to build suspense or to mirror the duality of the characters?

Holmes' approach felt more aggressive here, which made me question the line between justice and revenge. How do others interpret his actions in this story?

The depiction felt intense and realistic, making me wonder whether Doyle drew inspiration from actual historical groups or created it entirely from imagination.