I felt lots of trepidation. My comfort zone is Doc Martin! Martin Clunes tells us about his challenging new role as Sherlock Holmes creator Arthur Conan Doyle in a tale which sees the author becoming a detective himself.
The story is told with Martin Clunes playing Doyle, and it's as spooky, unsettling and highly entertaining as any tale from 221b Baker Street.
"I felt loads of trepidation about the role," admits Martin, 53. "I'm just the bloke from Men Behaving Badly, and my comfort zone is Doc Martin or documentaries about animals."
But from the moment his Doyle comes on screen with an authentic sounding Scottish burr, a twitchy moustache and elegant tweed suit, Martin is entirely believable as the celebrated author.
The three-part series begins in 1906, as Doyle is grieving over his wife Louisa who has died after a long illness. It takes his trusted manservant Alfred to raise his spirits. He does so by encouraging Doyle to help solicitor George Edalji clear his name after he has served a prison sentence for mutilating animals and writing obscene letters.
"I think he seized on this case as a distraction," Martin explains. "It triggers something in his imagination and he gets fired up. He tries to use Sherlock Holmes' forensic methods to solve the case. So the story is how the author of detective novels turns into a detective himself... or tries to."
And just like in a Sherlock Holmes tale, there's even more to it than that. The story is GREAT SCOT: Sir Arthur Conan Doyle "An an adaptation of Julian Barnes' acclaimed novel, and the drama will also show how the difficulty in overturning Edalji's conviction was influential in the campaign for the creation of England's Court of Criminal Appeal in 1907.
The drama sees Doyle - who died in 1930 at the age of 71 - become convinced that Anglo-Indian Edalji's conviction was the result of a racially-motivated campaign against him and his family. But while Doyle wants to create a big stink about this miscarriage of justice, the man at the centre of the case is just quietly praying to have his name cleared.
"George had been released from prison after serving three years, but he was not allowed to practise law," says Arsher Ali, who plays Edalji.
"That destroyed his ambition in life. Early on, Arthur Conan Doyle says a lot about compensation and finding the person who committed the crime, but I don't think that was what George wanted. There is a line in our adaptation, and I think in the book, where he says, 'I haven't been focusing on who might have done it or who's guilty. I have been focusing on proving my innocence'."
Arsher, who is married to Emmerdale actress Roxy Shahidi, is relishing the chance to take part in a period drama, having just played a ruthless journalist in BBC1's The Missing.
"I have always wanted to do something which was set in this type of period because a lot of the stuff I do is modern," he says.
But later this year, Ali will be acting in a very different era as he joins the cast of Doctor Who. "I'm not allowed to tell you anything about it," he says when pressed for details.
The cast is rounded out by Art Malik (of Jewel In The Crown fame) who plays George's father.
"We were so thrilled when we knew we had Art," says Martin. "On his first day on set, Arsher said, 'It's like having royalty arrive, isn't it?'. And now Art is lobbying for a role on Doc Martin!" Clunes is hoping that this show might follow in Doc Martin's footsteps, which has just started filming its seventh series in Port Isaac, Cornwall.
"This wasn't the only investigation Conan Doyle became involved in," he says. "If people enjoy this, I am sure we could adapt some more of those cases."
"An injustice triggers Doyle's imagination and he uses Holmes' methods to solve it"
THE CAP FITS: Martin Clunes as Conan Doyle