Thus "It Walks by Night" begins on a note of supernatural horror. It the first of more than 70 novels by Carr, and the first of his mysteries featuring the suave, Mephistophelean M. Henri Bencolin, 'juge d'instruction' of the Seine, the head of the Paris police and "the most dangerous man in Europe."
Carr began his writing career, at the age of twenty-five, with his Inspector Bencolin mysteries. M. Bencolin was even spotted in some of Carr's earlier college stories published in the school newspaper, "The Haverfordian." (It may surprise you to learn that John Dickson Carr was American).
"It Walks by Night" really begins when the police burst into the card room of a sinister Parisian gambling establishment, and spot the severed head of the Duc de Saligny staring at them from the centre of the empty room. The remainder of his body is kneeling on the carpet, as though he had been waiting for his executioner's blow.
This is Carr's first mystery and also his first 'locked room' mystery, for which he became justifiably famous. Both doors of the card room were being watched by the police, including M. Bencolin, himself. The window to the card room was absolutely inaccessible and had not been entered, and there were no secret passages by which an entrance could be made through the walls. Yet within the space of ten minutes the executioner had entered the room, had severed the Duc de Saligny's head from his torso, and had escaped without leaving a clue and without having been seen by anyone.
Hashish, hysterical women, a murderous ex-husband escaped from the insane asylum, and several love triangles (actually one of them is a pentagon) feature prominently in this story of a bride whose husband is beheaded in a gaming establishment on their wedding night: her "eyes had the bright shine of terror as she stared at the thing that lay at her feet: the severed head of the Duc de Saligny!"
As is common in Carr's M. Bencolin stories, "It Walks by Night" pays homage to Poe, most specifically his story "The Cask of Amontillado."
In his Bencolin novels, Carr seems fond of spectacularly gory murders and lurid settings for his Satanic detective. The American, Jeff Marly (Bencolin's muscular Watson) states that in Bencolin's hands, "a thousand facets came glittering out of the revolving jewel of Paris--lights and shadows, perfume and danger...abbey, brothel, and guillotine." This story takes place in Paris in 1927 in an atmosphere of hysteria, jazz, a hint of werewolves and impossible murders, ambergris-scented rooms, and a beautiful woman looking up into Jeff's match-flame: "Except for a kimono over one shoulder, she was unclothed, a breathless mystery of flesh and shadow."
A breathless mystery, indeed.