<p>This work contains an active table of contents (HTML), which makes reading easier to make it more enjoyable.<br><br>First published in 1890, The Sign of Four is Sir Arthur Conan Doyle's second book starring legendary detective Sherlock Holmes. The story is complex, involving a secret between four ex-cons from India and a hidden treasure. More complex than the first Holmes novel, The Sign of Four also introduces the detective's drug habit and l...