The Cat o' Nine Tails (Italian: Il gatto a nove code) is a 1971 English-language Italian film directed by Dario Argento, adapted from a story by Dardano Sacchetti, Luigi Cozzi, and an uncredited Bryan Edgar Wallace.

[5] Although it is the middle entry in Argento's so-called "Animal Trilogy" (along with The Bird with the Crystal Plumage and Four Flies on Grey Velvet), the "cat o' nine tails" does not directly refer to a literal cat, nor to a literal multi-tailed whip; rather, it refers to the number of leads that the protagonists follow in the attempt to solve a murder.

He attempts to blackmail the individual, but the thief pushes him in front of an arriving train, killing him.

Reporter Carlo Giordani has been covering the break-in investigation and writes an article about Calabresi's death, including the photo.

Franco "Cookie" Arnò, a middle-aged blind man who was once an ace reporter, and his niece Lori visit Carlo after reading the article.

Carlo tries to look for Dr. Braun, whose escape made him a suspect, but at his boyfriend’s house, he’s found stabbed to death.

The killer calls Franco and Carlo, revealing that he has kidnapped Lori and will kill her unless they stop investigating.

Carlo follows a trail of blood to the roof and finds Casoni, the killer, still bleeding from Franco's attack.

Franco stops him with his cane blade; Casoni confesses that he initially broke in to replace the records that showed he tested positive for the XYY chromosome.

Dario Argento and Dardano Sacchetti together mapped out the plot for The Cat o' Nine Tails, and split the writing of the screenplay between them.

The site's critical consensus reads, "The Cat O'Nine Tails is a solidly entertaining Argento outing elevated by a well-chosen cast and the director's distinctive visual style.