Dario Argento’s first films – those constituting the so-called ‘Animal Trilogy’ – should be considered as works belonging to the era in which they were made, more so than the successive canonisation of the director as an international maestro of horror-thrillers. From this perspective, Il gatto a nove code is no exception. We find elements, subsequently developed over time, that will become integral to Argento’s fame, as well as marks of his auteurship: first, the subjective long shots of the killer’s movements, intercut with extreme close-ups of his pupils, serving as a mechanism to trigger suspense. Then, the metatextual role of the puzzle, the mystery to be solved […]. And finally, the Hitchcock quotations, taking form here in a precise intertextual reference to the famous glass of milk scene in Suspicion (1941).
However, in Il gatto a nove code there is much, much more. For example, the acute sense of urban alienation found throughout the film, constantly adding a subtext to the narrative. It emerges on a figurative level, through alienating shots of the architectural compositions and the cold geometric forms, a sort of metaphor for cosmopolitan loneliness. Narratively speaking, the theme of solitude is the hidden soul of the film, permeating and unveiling itself as events unfold. […] In short, as depicted by Argento, society is but the random crossing of trajectories of human monads, almost always dictated by less than noble circumstances, such as greed, resentment and fear.

Leonardo Gandini, in Argento vivo. Il cinema di Dario Argento tra genere e autorialità, edited by Vito Zagarrio, Marsilio, Venice 2008

The cemetery sequence is very beautiful, tense, surprising and humorous. With that scene, I inaugurated what I call the series of ‘long sequences’; long, as they can last as long as half an hour. They are constructed to perfection, with lengthy and exhausting crescendos. […] The subjective shooting technique was something I had used in abundance in L’uccello dalle piume di cristallo (The Bird with the Crystal Plumage). Using it again in this film was simply me following my evolutionary path. Il gatto a nove code is a transition film, as it allowed me to experiment with the means at my disposal. I was trying to understand my limits and my potential, like a good athlete testing himself over long distances to understand his specialisation.

    Dario Argento, Confessioni di un maestro dell’horror. Un libro intervista di Fabio Maiello, Alacrán Edizioni, Milan 2007