'Sherlock' Season 4 release date, plot spoilers: Benedict Cumberbatch to have special new sidekick

Initial photos on the set of the upcoming fourth season of "Sherlock" are in, and it appears that Benedict Cumberbatch's genius detective character will be getting himself an unlikely ally. James Watson has always been Sherlock's trustworthy sidekick since Series 1 debuted six years ago, and with the arrival of a new companion, things are expected to be more fun and exciting. Of course, Watson will remain as Sherlock's true ally.

A promotional still for "Sherlock" Series 4 released by BBC reveals Sherlock Holmes bonding with an adorable canine. Screen Rant reported that this new dog companion of Sherlock is reminiscent to the same furry sidekick of Sherlock Holmes in one of Sir Arthur Conan Doyle's classic detective stories, "The Sign of Four."

In the original "Sherlock Holmes" novel, Sherlock has a sniffer dog named Toby that helps him resolve some of London's most bizarre cases. It looks like this new addition to BBC's hit TV series will be a big help for Sherlock and James Watson with his heightened dog senses. It was noted, however, that the dog companion is just a temporary sidekick and Watson's role in the series will not be replaced.

"Sherlock" Series 4 is set to arrive in early 2017, and the whole cast is currently finishing the new chapter amid its lead stars having huge commitments in Hollywood. It can be recalled that Cumberbatch's upcoming Marvel feature film this year, "Doctor Strange," has limited the actor's availability for the past few years, thus putting "Sherlock" in danger of being further delayed for Series 4, or even getting canceled. Fortunately for the fans, Cumberbatch made it possible to return in the series alongside Martin Freeman, who plays the character of Watson. Freeman himself had been very busy shooting for Peter Jackson's "The Hobbit" trilogy, where he played the role of Bilbo Baggins.

Sadly, with the increasing demand for Cumberbatch in Hollywood, "Sherlock" Series 5 may not actually happen. The Morning Ledger quoted "Sherlock" series creator Steven Moffat saying that the actor's limited availability could lead to Series 4 being the last for "Sherlock."

"I don't know how long we can keep it going. I'm personally willing but I'm hardly the main draw. I would be moderately surprised if this was the last time we ever made this show. But it absolutely could be," Moffat revealed in an interview.