Some spoilers throghout
I’ve been thinking about the show lately, and how it should end. Unfortunately, there is a high probability that it will get canceled by the end of season four.
I think that in the series finale (two or three parter, or one episode ninety minutes or two hours long), several murderers, the ones that Sherlock and Joan have put away prior in the series, should escape from prison, having somehow planned that together. They gang up together, planning to take revenge on Sherlock and Joan before fleeing the country. I think that those prisoners should be: Adam Kemper from 1x3 “Child Predator”, Heather Vanowen from 1x8 “The Long Fuse”, Jeremy Lopez from 1x10 “The Leviathan”, Tanya Barret from 2x2 “Solve For X”, Ezra Kleinfelter from 2x3 “We Are Everyone”, Dana Kazmir from 3x5 “Rip Off”, Del Gruner from 3x12 “The One That Got Away”, and Dania Powell from 3x15 “When Your Number’s Up”.
(A British tourist was murdered in New York an episode prior, and there was evidence that he was planning to track down Kitty, wanting her to look into the unsolved rape/murder case: the victim was his sister. It turns out that was also estaged by Del so Kitty would return to New York-which she did-and he could kill her after escaping from prison. So, yes, Kitty would be present too, only nit too heavily featured. And no, she wouldn’t get killed.)
So, throughout the finale, Adam and Del get killed and others get arrested, but Tania demands the prosecution to give them an immunity and release them, since she has managed to hack into the witness protection database prior to getting arrested (easily-she solved P vs NP after all), causing all the information to become public in twenty four hours. She is the only one who has a code that would stop the process. FBI wouldn’t have time to re locate all the witnesses or figure out how to break the virus in twenty four hours. Not even Everyone is up to the challange. So Sherlock would have to reach out to Moriarty for help, having her pull her ties to ensure that some of the criminals will leave witnesses alone and have some of her henchmen cause a part time blackout in some parts of the city, giving FBI enough time to re locate the witnesses and eventually defeat the virus.
That way we would have an exciting series finale with some nice callbacks to old times and Moriarty would still be involved despite not being a major part in Sherlock’s last cases in the original stories. I think that maybe early in the last seasons Sherlock would deal with a case that would really shake him and he would think about retiring from the detective work, maybe move back to London, but in the end decide to continue working with Joan.
Maybe the subplot in season finale could be Marcus getting married. I’d like seeing Thomas end up from Terry D’Amico from 1x7 “One Way To Get Off”, since he is apparently divorced as off season three and I’ve never seen much chemistry between him and his wife. I have mixed feelings about both possibilities, keeping Sherlock/Joan relationship platonic or developing it into something more. Maybe they could find a middle ground, such as having Sherlock and Joan kiss at the end of the episode. Of course, have minor characters appear throughout the episode, assisting in the investigation, most of them being on the wedding at the end: Alfredo, Randy, Harlan, Ms. Hudson, Gay etc.
Yes, hard to pack it all in season four, but it would be pretty satisfying. Of course, there is always the possibility that Elementary will have a short final season, like “The Mentalist”. Or even a complete fifth season. But whenever it ends, I hope that it goes out with a bang.