The Cat o' Nine Tails 1971

Despite a couple of good scenes, The Cat o' Nine Tails is easily the weakest of Dario Argento's early giallo & horror movies. Where Argento's other movies tend to make the protagonist involved or even complicit in the murders, in this case we get two characters investigating the case out of professional interest and just plain nosiness. The central mystery itself isn't terribly interesting with the solution being almost arbitrary. There are attempts to spice things up with nature vs nurture arguments (is the killer driven by the genetic MacGuffin or just trying to cover it up?) and an attempt at a running theme around eyes, but these aren't developed, just dropped in.

Usually there'd be a few flashy murder setpieces to drive audience interest, but apart from a bravura scene at a train station, the other murders are too repetitive and almost seem perfunctory. Attempts at sexy banter between James Franciscus and Catherine Spaak make similar scenes in Profondo Rosso seem like Howard Hawks. It's overlong and often drags. The scenes involving gay characters are as retrograde as ever.

A completely gratuitous car chase, on a level with the kind of thing seen in a decent poliziottesco of the same period, was the highlight of the movie for me. I quite enjoyed the climax, which features a decent rooftop chase and a nicely abrupt finish. Ennio Morricone's score helps the movie through some of the dull patches; I miss it in the scenes where it stops.

Argento doesn't play to any of his strengths in The Cat o' Nine Tails. It needs more weird touches, more genuine perversity, more colour, more interesting camera movements, and less talk. It's still better than anything he's directed since about 1996.

The Cat o' Nine Tails is an improvement over Argento's Bird with the Crystal Plumage, but not by much.
Similar to TBWTCP, TCONT is a giallo where a civilian is playing detective - maybe a little more plausible this time around, for reasons I will cover in a moment.
The movie starts with Franco, a blind man, and his... adopted daughter - I think. A series of crimes lead Franco to seek the assistance of Carlo, a reporter, in solving the mystery. As before, someone who is not involved in law enforcement putting themselves in harm's way to solve a murder case is just ridiculous; though, at least, this time we're dealing with a reporter, and a former reporter, so they may be slightly more accustomed to snooping around to get a story, but that does not make them Batman or Daredevil.
The movie is almost two hours long, and it didn't need to be. It's a very simple story, laden with more characters than necessary - for example, Carlo, and Franco could have just been combined; the only reason Franco was there was because of his "daughter."
So, the killer is Casoni. Okay. By the time that was revealed, I had forgotten who he was. Turns out he has an XYY chromosome, which - according to the scientists in this movie - means he is prone to murder. If this information was found out, he'd lose his job. Solution: murder people. Problem solved. If that sounds dumb as fuck, that's only because it is.
Don't go into this looking for horror. It's 99% mystery, with limited kills - very tame.