series 3 of sherlock: john marries mary morstan off-camera, the show mocks all the fans who kept the hype up during a two year hiatus, mary turns out to be an assassin who shoots sherlock, during which time he has a near-death-experience dream about his dog redbeard who was put down. also there’s a weird scene where john is revealed to be attracted to danger and so he dated mary because he was subconsciously picking up the fact that she used to be an assassin. also the series ends with sherlock committing murder in front of witnesses to save john and mary.
christmas special: sherlock goes on a bender where he hallucinates a victorian-era case, the episode ends with moriarty seemingly returning via social media and mycroft making a cryptic reference to “the other one.” oh, also any consequences from sherlock committing murder are immediately negated.
episode 1: mary is killed due to her assassin past, but no one really cares since she’s only been in the show for all of four episodes. she keeps coming back as a recorded voice/hallucination.
episode 2: john goes to a new grief counseler. also he keeps hallucinating mary. sherlock is told to solve a murder by the murderer’s daughter, but it turns out that while the murderer has a daughter, it’s not the woman who gave him the case to solve! eurus, sherlock and mycroft’s sister, has simultaneously masqueraded as john’s grief counseler and the murderer’s daughter and a random woman who keeps following sherlock because she’s a master of disguise! (to be fair, this is a legitimately cool reveal and I genuinely didn’t see it coming)
episode 3: HOO. FUCKING. BOY. eurus is sherlock and mycroft’s sister who’s been in a prison for the criminally insane for decades. mycroft has withheld this knowledge from both sherlock and their parents by claiming she died in a fire she started. turns out she’s able to hypnotize people with ???? her superior intellect ???????? and so even talking to her makes people want to do things for her like commit murder ????????? and so she’s somehow able to do things like escape from her scary island prison and then take herself back, blow up baker street, kidnap multiple people, and then pull Saw-esque morality problems on Mycroft and Sherlock and John where she just murders people for funsies with no apparent motive. IT IS DURING THIS SEQUENCE THAT IT IS REVEALED THAT SHERLOCK HAD A HUMAN BEST FRIEND THAT EURUS MURDERED BUT REWROTE HIS OWN MEMORIES TO IMAGINE IT WAS A PET DOG WHO DIED.
Y’ALL. IT IS SO DUMB. IT IS SO DUMB THAT THE FANDOM GENUINELY HAD A CONSPIRACY THEORY GOING FOR A WHILE THAT THERE HAD TO BE A SECRET FOURTH EPISODE - OF A SHOW THAT ONLY EVER HAD THREE EPISODES PER SERIES - BECAUSE THERE WAS NO WAY THAT SOMETHING THAT BAD COULD BE THE FUCKING FINAL EPISODE.