Following the death of Mary Watson, John and Sherlock are estranged. John is in therapy and hallucinating conversations with Mary, while Sherlock has spiraled back into heavy drug use. Sherlock recap: Season 4, Episode 2 - Entertainment Weekly
" The Lying Detective ," the second episode of Sherlock 's fourth season, is widely regarded as a return to form for the series, featuring one of the most chilling villains in the show’s history. Written by Steven Moffat and directed by Nick Hurran, the episode is loosely based on Sir Arthur Conan Doyle's short story, " The Adventure of the Dying Detective ". Sherlock_in_streaming_s04e02