Episode one, The Empty Hearse, will involve scenes set on the London Underground rail system and is influenced by the recently rediscovered missing Doctor Who adventure The Web of Fear, says Gatiss.
The BBC revealed this week that the Patrick Troughton Who story has been recovered and restored to its former glory after having been lost for 45 years, and Gatiss marks it out as having had a significant influence on him – and Sherlock.
"I am obsessed with the Tube and I think it all comes from that story when I was a kid," said Gatiss at the launch of the recovered Doctor Who adventures. "The first episode of Sherlock is explicitly about the London Underground for exactly that reason – because I love The Web of Fear!"
Read more at the Radio Times