A loose adaptation of both The Empty House and The Master Blackmailer by Sir Arthur Conan Doyle.
Excerpt from BakerStreetWiki: Holmes is hired by the débutante Lady Eva Brackwell to retrieve compromising letters from a blackmailer: Charles Augustus Milverton, who causes Holmes more revulsion than any of the 50-odd murderers in his career. Milverton is "the king of blackmailers" and he makes his living out of blackmail. He demands £7,000 for the letters, which would cause a scandal that would end Lady Eva's marriage engagement to the Earl of Dovercourt. Holmes offers £2,000, all Lady Eva can pay, but Milverton insists on £6,000. It is worth £2,000 to him to make an example of Lady Eva. Holmes resolves to recover the letters by whatever means necessary, as Milverton has placed himself outside the bounds of morality.
