The Sign of the Four（四签名）

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 leaves breadcrumbs for the reader that lead toward the final resolution.

亚瑟·柯南·道尔：英国人，世界著名小说家。因成功地塑造了大侦探歇洛克·福尔摩斯的形象而成为侦探小说历史上最重要的小说家之一。除此之外，他还写过多部其他类型的作品，如科幻小说、悬疑小说、历史小说、爱情小说、戏剧和诗歌等。