"Sherlock" season four has ended, culminating a run of episodes that have kept fans on their toes with surprise deaths, enormous twists and a shocking return. The show's creators recently talked about the finale and possibilities for the next season.

The popular BBC series has housed many inexplicable deaths, which Sherlock Holmes (Benedict Cumberbatch) has had to infer around, even in the face of threats to his own life. Luckily, none of the show's leads died, but fans learned that someone very important to Sherlock had. In addition, the show's approach to the revelation was rather mind-boggling, says Comic Book.

The surprise came about when Sherlock met his sister Eurus (Sian Brooke) at a prison called Sherrinford. In their conversation, fans learn that it was not Sherlock's dog that died when he was younger, but his best friend Victor Trevor. Eurus killed Sherlock's best friend by drowning him.

She was envious that the boy got more attention than her, and Sherlock was all but unaware of her solitude. The incident left Sherlock devastated, and Mycroft (Mark Gatiss) chose to rewrite Sherlock's memories and have him forget Eurus completely. As a result, Sherlock grew up believing that it was his dog that died and not his best friend.

On January 12, showrunners Steven Moffat and Mark Gatiss Steven showed up on the BFI's (British Film Institute) special preview of the "Sherlock" episode titled "The Final Problem," prior to its airing on BBC One. The two broke down all of the surprises, as well as teased the possibility of an unconfirmed fifth season.

With Season 4 now complete, fans are egging on for news about a fifth season. Will "The Final Problem" the series' last show? Moffat thinks that this is a possibility, as reported by Independent. He said that if "The Final Problem" is the last time, he is not planning on it to be. However, it is possible that it would be the end, he teased.