 Argento 's protagonists in his giallo films almost always suffer from vision impairment of some kind . It is these characters ' chronic inability to find the missing pieces of a puzzle ( the puzzle being the solution of a murder or series of murders ) that generally provides much of the films ' narrative thrust . Most obviously is the blind Franco Arno ( Karl Malden ) in The Cat o ' Nine Tails , who must use his heightened aural sense in combination with visual clues supplied to him by his niece to solve a mystery . In The Bird with the Crystal Plumage , Sam <unk> ( Tony <unk> ) witnesses a murder attempt but admits to the police that something seems to be " missing " ; as the film 's surprise ending makes clear , he did not " miss " anything , but simply misinterpreted what happened in front of his eyes . In Deep Red , Marcus ( David Hemmings ) has a similar problem in both seeing and not seeing the murderer at the scene of the crime , and does not realize his mistake until it 's almost too late . This recurring theme , according to Douglas E. Winter , creates " a world of danger and deception , where seeing is not believing " . 
