The most obvious source of this episode, to which its title alludes, is "The Adventure of the Empty House", in which Sherlock Holmes returns from his "Great Hiatus", having allowed everyone to believe him dead to root out the rest of Moriarty's criminal organisation. In both the story and the episode, Mycroft helps Sherlock fake his demise. The villainous Moran in this episode is named after Colonel Sebastian Moran, the villain of the original story. In "The Adventure of the Empty House", Watson first encounters Holmes disguised as a heavily accented and bearded book salesman with a shop on the corner of Church Street, who offers Watson some books. In the episode, John encounters a man as his patient who owns a DVD shop at the same location; the man offers to sell him pornographic DVDs with titles almost identical to the books Watson was offered by the disguised Holmes in the short story ("Tree Worshippers", "British Birds", "Catalysts", and "Holy War"). John falsely assumes it is Sherlock in disguise, with embarrassing results. It is also a reference to a scene from The Spider Woman starring Basil Rathbone and Nigel Bruce. Moffat and Gatiss have cited the film series as another source of inspiration when writing Sherlock. The remainder of the episode's storyline is largely original.
