I saw this on The Horror Channel.
Having seen a few Dario Argento horror flicks on this channel now, I would dare say that Cat O' Nine Tails is the most restrained, at least in the gore/violence stakes, of those I've watched. There are moments of extreme but swift, clever nasty bits, though.
I guess you'll be watching this cos it is by this so-influential 'Italian Hitchcock' maestro rather than for its story, but having said that, it's decently far-fetched enough but with enough relevance to paranoia around government testing of miracle drugs and all that...
It looked to me to have been made in English, rather than dubbed, or could just that the brilliant, understated performance by Karl Malden was and everyone else were dubbed after. He plays a blind, retired journalist, who has a young orphaned girl as his visual aide and along with a current newspaper reporter,(James Franciscus) they uncover all these secrets after a man, they suspect, was pushed under a train, rather than falling and then, other murders.
I'm no expert on the horror genre but would dare say that this still has signs of the director's visual stylish daring, but is less operatic than some of his, being more workmanlike and 'American'. It still works well, but is more akin to a crime thriller than out-and-out horror, though we do get moments of terror and suspense and the odd twist in the tale.
This might be a lesser Argento (number of reviews and score on IMDb) but is still a heap better than many Hollywood affairs but somehow, doesn't have that magic ingredient that his best movies have. Quite good, but not great.