The fourth season of BBC's crime drama Sherlock, starring Benedict Cumberbatch, premiered on Jan 1. [Photo provided to China Daily]

Life has been busy for the stars of Sherlock since the series premiered in 2010, with UK TV producers Steven Moffat and Mark Gatiss applying new London style and contemporary quirks to Arthur Conan Doyle's famous consulting detective. Its fourth season－there have been breaks－premiered on New Year's Day.

Benedict Cumberbatch plays a 21st-century Holmes in Sherlock.

Martin Freeman, the series' Dr John Watson, has gone from a guy you may have seen on the British version of The Office (2011-2013) to playing Bilbo Baggins in three Hobbit movies.

Cumberbatch has, among other things, played Khan in Star Trek Into Darkness (2013), the title role in Doctor Strange (2016) and codebreaker Alan Turing in The Imitation Game (2015).

Doyle wrote 60 Holmes stories, but the world has deemed that insufficient, and many other hands have filled out the tale.

Sherlock selects plot elements and incidental details from the original stories, and mixes and mashes them together, adding new ingredients to taste, as when a chef plays with modern variations on traditional cuisine without letting what's new obscure what's old.

The Six Thatchers, the first episode of the new season, is partly based on Conan Doyle's The Adventure of the Six Napoleons, with busts of Britain's Iron Lady replacing those of France's Little Corporal. There are references to the original story's missing black pearl of the Borgias, but it is only one of many threads and complications to follow and trip over.

The new episode picks up on the heels of last January's The Abominable Bride, a Victorian-era dream interlude that in turn picked up on the heels of the third season finale, His Last Vow, which premiered two years earlier.

To further confound time, Bride takes place in the last minutes of Vow, as Sherlock, flying off into exile, is recalled to England when the face of the supposedly late Professor Moriarty appears on television screens all over England over the title Did you miss me?

Sherlock's aborted exile followed his killing of a blackmailing newspaper publisher－"I'm not a hero," he announced, then; "I'm a high-functioning sociopath"－and it gives away nothing to say that this problem is quickly dispensed with in Sunday's episode in order for our heroes to get on with new business, solving a string of cases in montage, while waiting for Moriarty to strike.

John, meanwhile, who last season wed Mary (Amanda Abbington)－"a retired super-agent with a terrifying skill set", but also a lovely person－is being worn down by new fatherhood.

There is more of a bromance－if an inarticulate, kind of embarrassed one－between the partners than in other versions. Sherlock calls Watson "John", and Watson calls Holmes "Sherlock". That Sherlock may be harboring the semblance of a caring person somewhere in the cold, cool chambers of his mind is something Moffat and Gatiss like to play with, for character and comedy.