It Walks By Night, first published in 1930, is the first detective novel by John Dickson Carr.

[1] It has been compared to "The Murders in the Rue Morgue" by Edgar Allan Poe.

[2] A closely guarded room in a Paris gambling house, a mangled body on the floor, a severed head staring from the centre of the carpet; someone had entered that room, killed and escaped all within ten minutes.

Ten minutes after the Duc de Saligny entered the card room, the police burst in – and found he had been murdered.

In a 2019 review in the Times Literary Supplement, Heather O'Donoghue writes that while the setting is "unexpectedly hard-hitting", "the novel itself is not easy reading" and that character development suffers, in part due to the tradition that "the culprit should be the least likely suspect".