In The Crimson Fog, French master of the impossible crime novel Paul Halter offers his take on the Jack the Ripper mystery.

When did you first become fascinated with impossible crimes?

As far back as I can remember, I’ve always been fascinated by mystery. The fairy tales, with the evil witches and horrible ogres, that my parents and grandparents read to me fascinated me but made me tremble with fear. And when I started to read, I always chose mystery stories. I didn’t discover locked-room wizard John Dickson Carr until later, but his books led to my own.

How do you go about writing?

The starting point may be a news story, a particular theme, a mysterious place, a trick for a perfect crime. I never start writing before I’ve mapped the whole story out, and become comfortable with the overall atmosphere of the book. Explanations of perfect crimes, sophisticated alibis, and locked room murders don’t just happen—they’re part of a carefully constructed plan. I also need to believe in my story, so that it makes me shiver just as the earlier ones did in my adolescence. In that sense, I’m not really a professional writer. I just can’t write a story dispassionately: I must believe in it.

Do you develop an impossible scenario and then try to figure out a plausible solution?

I always have a few ideas put aside, carefully noted on bits of paper I keep in an old shoe box. But it’s also very exciting to start with a challenge, to imagine the most impossible crime possible and to try to find a solution. In The One-Eyed Tiger, I attempted a triple-locked room—inaccessible, sealed, and an eye-witness to the crime. I owe one novel to a friend, who proposed a crime in a room in which the only exit was covered by a spider’s web. When I get what seems to be a clever idea, I make sure I test it out, using lighting effects, mirrors, locks, windows, etc.

Why write about the Ripper?

The dark alleys with uneven cobblestones, the baleful light of the gas streetlamps, and the insidious fog hiding a lurking murderer—it’s the quintessential mystery. His crimes were hideous and revolting, arousing the voyeurism that lies dormant in each of us. A policeman stumbling on the steaming entrails of the murderer’s last victim, in a place where there had been no one five minutes earlier—that cannot leave you indifferent. On top of the horror, there is the mystery, elevated to a degree never surpassed. Which mask hides the identity of the monster? Why the terrible butchery? How can he escape capture when the whole of Scotland Yard is on his heels?