David Pirie is the author of three mysteries in which a young Arthur Conan Doyle plays Watson to his real-life mentor, Joseph Bell, the model for Sherlock Holmes.

Why did you decide to write mysteries about the creator of Sherlock Holmes as a young man rather than straight pastiches?

When I read the Holmes stories as a child, I was told that Doyle treated writing them as a game, he never took them seriously. Even then, that explanation didn't satisfy me—I felt there must have been something more at work. The stories were too intense and had too much emotion in them for me to really believe that they were just a little indulgence on Doyle's part. Much, much later, when I was a screenwriter, I tried to persuade the BBC to film the first Holmes story, A Study in Scarlet, where he meets Watson. I wasn't successful, but they did say they might be interested in doing something on Bell.

How did you go about creating your Bell and Doyle for the BBC?

When I started, I assumed—because of the legions of Doyle admirers worldwide, and the many biographies of him that had been written—that everything that could be known about him was known. But then I had a look at what there was about Bell and was absolutely astonished that Doyle's letters and personal papers weren't available; the existing biographies were themselves pure detective work. I traveled to Doyle's home in Edinburgh and gradually pieced together in my mind the idea that the genesis of the emotion in the books I'd seen as a child must have come out of something that was going on with Doyle at the time he met Bell. The more I read, the more I came to believe that a whole lot of things about Doyle's life had been covered up.

In The Dark Water, Bell is active as a criminal investigator, much as Holmes was. Is there anything in the historical record to support this?

Yes, although you have to look hard for it. One murderer, on the gallows in Edinburgh, said, right before his execution, that he specifically wanted to single Bell out as the man who caught him. Bell had apparently insisted that his name be kept out of the trial, although records do show that he had come into the case and steered it in the right direction. Doyle must have known of this incident, and yet, strangely, never refers to it. The only thing that makes sense to me is that he had promised Bell not to.