MacBird’s second Sherlock Holmes adventure, Unquiet Spirits (Collins Crime Club, Oct.), explores the detective’s emotional side.

What inspired you to write your first Holmes novel, Art in the Blood?

In 2012, I had just survived something quite trying, and I have always found solace and recovery in maximally challenging artistic work. I set out to test my writing chops with something I knew would be devilishly hard—a long-form Sherlock Holmes story, emulating Conan Doyle, all facts and timeline consistent with canon, but adding a deeply personal dimension without overstepping or destroying the mystery of Holmes himself. I have loved Sherlock Holmes since age 10, and so I aimed to write the novel I most wanted to read.

What difficulties did you face?

Holmes must be ahead of the reader and Watson. The forensics of the era are different, everything requires massive research, and a full-length Holmes novel demands intricate plotting to convince the reader that even the most brilliant detective in the world can’t solve everything by page 30. The crime and the deductions are the hardest parts to get right. How Holmes deduces and in what order to present the clues to the reader pose the toughest challenge.

What were you trying to do by filling in Holmes’s backstory?

Holmes himself is a mystery, and readers recognize him as a bit of a damaged bird. But why? What happened to him? Holmes’s celibacy and his feelings for women have intrigued readers for over a century. Abstinent by choice? It’s such a dramatic choice and a lonely one. While he jokes about the incomprehensible minds of women in the originals, my interpretation is that he doesn’t really understand women. This puts us in very dangerous territory—Holmes readers are picky about this. In my Holmes world, he will never marry. But he’s a human being and one with deep and complex feelings. He kept Irene Adler’s picture, after all, calling hers a “face that a man might die for.” I decided to create an incident in his past so dramatic, so heartbreaking, and so in character that it explains his lifelong hesitation.

Is there a historical basis for the rivalries among Scottish whiskey manufacturers you depict in Unquiet Spirits?

Absolutely! When brandy and wine skyrocketed in price, innovative Scots marketing geniuses—James Buchanan and Tommy Dewar—took on London to set up whiskey as the new drink of society. Among Highland distilleries, before they became big business at about this time, strong rivalries led to sabotage between some of the rival families. All that was very real.