'Sherlock' season 4 spoilers news: Toby Jones playing villain Culverton Smith; new cast additions, last episode director confirmed

The latest on the much anticipated crime drama series "Sherlock" has been announced. Toby Jones, previously revealed as joining the cast for the upcoming season, will be playing one of the finest Doyle villains, Culverton Smith. The character comes from the "The Adventure of the Dying Detective," and Sherlock Holmes believes him to be responsible for the death of the former's nephew.

Said to be a tropical disease expert of sorts, the villain sent a spring-loaded pin which had been infected with a fatal disease by post to Sherlock's Baker Street, with the intention of killing the foremost detective. The detective, in turn, suspected foul play and decided he would feign illness to trap the suspect and have him arrested for his previous misdeed. To make sure the ploy would work, the master sleuth tested the ruse on Doctor Watson who fell for it hard, leaving Sherlock fraught with worry over the possibility of losing his friend.

Jones will figure in "Sherlock" season 4, episode 2 which is being currently filmed with Nick Hurran ("His Last Vow," season 3's finale) directing.

Two more cast additions have been reported. The first one, very appropriately, is comedy actor James Holmes (popular as Clive in BBC's "Miranda"). Holmes will appear in episode one as a character only referred to as "Passenger."

The other actor set to make an appearance in "Sherlock" season 4 is a starrer from "Dr. Who," Daniel Hoffmann-Gill. No details have yet been revealed regarding his role.

It is assumed that the regulars from the past seasons, Benedict Cumberbatch, Martin Freeman, Amanda Abbington, Una Stubbs, Louise Brealey, Rupert Graves, and Jonathan Aris will return to reprise their roles in this upcoming run.

But perhaps the most awaited announcement of cast reprisal is of that malefactor who every fan must be missing. The last season's finale left with a cliffhanger of Moriarty's familiar chime, "Miss me?" but it is not clear whether actor Andrew Scott who played the character will be returning this season, although rumors have been espousing his return.

In other "Sherlock" news, the director of the third and final episode has been disclosed as Benjamin Caron ("The Crown"), rounding out the count for the whole series, with Hurran and Rachel Talalay, previously reported.

As to the focus and subject matter of the eagerly awaited "Sherlock" season 4, Mark Gatiss and Steven Moffat have teased it to be the "climax" of "the story we've been telling from the beginning."

Moffat also shared what the show's fans are likely to feel after watching season 4: "Hmmm ... desperate for series 5 ..."

He admitted it would be "an emotional upheaval" but also "hopefully enjoyable and fun."

He mentioned "tough," too, and it is sure to bring to mind what fans would be definitely heartbroken about, should the rumor hold true that they, as well as Dr. Watson and Sherlock, would be losing Mary this season.

"Sherlock" season 4 is speculated to return in January 2017.