If you don’t speak Chinese, you may not probably crack the secret message on “Sherlock” Christmas special.

The show’s creators hinted that the holiday special will be full of secret clues for Sherlock’s avid fans as well a secret message for its Chinese fans.

The Telegraph cited Radio Times interview with show creator Steven Moffat in which he said: “It’s a new story, but if you know the original stories, you’ll see that it’s fashioned out of quite a few others. As ever with us, we’ve chosen several and there are loads of references. One of them you have to be able to speak Chinese to get (it).”

According to The Telegraph, the show plays a vital part of BBC Worldwide sales and it is being watched by 98 million fans in China, who also gave special names for its actors such as “Curly Fu” for Holmes and “Peanut” for Dr. John Watson.

“Sherlock” has been sold to 200 countries and evidently popular in China despite only being available online rather than broadcast on TV, The Guardian noted.

The Christmas episode, titled “The Abominable Bride,” will go back to the Victorian era with a Sherlock ghost story. It stars Benedict Cumberbatch as Sherlock and Martin Freeman as Dr. John Watson.

Cumberbatch admitted that he initially thought the decision to set the special episode in 1895 was a mistake.

“I thought they’d finally lost the plot, jumped the shark … then they expanded the idea and pitched it to me properly and I think it’s fantastic. Absolutely brilliant,” Cumberbatch said.

In July, PBS released a teaser of the episode featuring Holmes and Watson returning to 221 Baker Street. In the teaser, Watson is also writing a novel, which Mrs. Hudson doesn’t enjoy.

The “Sherlock” Victorian-era Christmas special will be shown on New Year’s Day on BBC1 in the UK and PBS Masterpiece in the US, as well as some theaters worldwide.

“Sherlock” season three concluded in January 2014. The production for season four is expected to begin in spring 2016. No announcement has yet been made for its premiere date.