"Sherlock" season 4 is still a long way off, but thankfully, the cast and crew shared some juicy details about the highly anticipated return of Sherlock Holmes (Benedict Cumberbatch) to the small screen.

During the panel of the show at the San Diego Comic Con or SDCC, Amanda Abbington, who plays Mary Watson, revealed that the upcoming season is the "darkest" the show has ever been.

She explained that when they first read the script for "Sherlock" season 4, she and Cumberbatch were "overwhelmed" by how "shocking and amazing" the story was going.

Cumberbatch then added that it will be a "genuine emotional rollercoaster" although they emphasize that despite the darkness of the season, there will still be humor and jokes.

This is what Abbington reiterated in an interview with ComicBook.com, where she revealed that she cried a lot in "Sherlock" season 4. She reiterated that gags will always be part of the show.

"But that's juxtaposed with humor, as it should be because all great should have comedy in it as well, because that's life," the actress went on to explain.

As far as her character is concerned, Mary will deal with the outcome of her biggest and darkest secret now out in the open in "Sherlock" season 4.

During the panel, Abbington said that she loved the idea of the twist in Mary's story, having been revealed as an assassin. More about that will be delved into in the upcoming season.

In a separate interview, Cumberbatch also teased what to expect of relationships between characters come "Sherlock" season 4.

"It's the same strain of trademark humor, the relationships are strong and deep and really complexified by what goes on," the actor said.

"Sherlock" season 4 will once again put Moriarty (Andrew Scott) as the threat. Due to his mysterious and still unconfirmed return, Sherlock will spring into action to know if his rival is indeed back from the dead all while he protects his loved ones should he really is back.

Apart from Moriarty, Sherlock will also deal with a new adversary in the person of actor Toby Jones, whose character is yet to be officially named.