Italian horror master Dario Argento followed up his classic debut film, THE BIRD WITH THE CRYSTAL PLUMAGE, with his thriller, starring Oscar-winner Karl Malden. This who-done-it throws a lot of characters at the audience to keep us guessing and gives use two protagonists to keep us wondering who the main character is supposed to be. For Argento it's twofold, it often shows off his skills as a director, but also shows off his weaknesses as a screenwriter.
Franco Arno (Malden, A STREETCAR NAMED DESIRE) was a reporter before an accident turned him blind. Now he creates crossword puzzles and cares for a young orphan girl named Lori (Cinzia De Carolis, CANNIBAL APOCALYPSE). On the walk home one night, they overhear two men arguing in a car. Franco hears a story. The next morning he learns of a break-in at a near-by genetics facility. The company has discovered that an extra chromosome is linked to criminal activity, which could turn criminal prosecution and genetic screening upside-down. Reporter Carlo Giodani (James Franciscus, BENEATH THE PLANET OF THE APES) is assigned the story and Franco teams with him when murders start happening following the break-in.
As I mentioned, the story throws so many scientists at us that we have no idea who could be responsible or why. Franco actually references the title as the number of possibilities regarding the killings. But Giodani likes to focus on Anna Terzi (Catherine Spaak), the beautiful daughter of the head of the genetics firm. She's a reckless party girl who takes quickly to the handsome reporter. While Argento begins developing a romance between the reporter and heiress, he loses Franco and Lori's story. It's a credit to Giodani's character's charm and journalistic determination that he keeps us engaged in his less original storyline. A story about a blind man and little girl detective team has so much potential. Unfortunately, in the end, his blindness and her age simply turn into plot points.
For the most part, Argento takes his time building suspense. There is a great Hitchcockian sequence regarding milk that creates great tension. Same can be said of the sequence where Giodani hires a thief to help him break into an office. He always clues the audience in that the killer is lurking somewhere with a jump cut to an extreme close-up on an eye. But at the end, Argento rushes to his conclusion with contrivance and the audience is left wondering "that was it?' when the credits start rolling.
Argento himself has said this is the least favorite of his films. But I wouldn't call it his worst myself. Even with two lead characters, he does make us care about both of them. He wraps the viewer up in his murder mystery pretty tightly, but drops the ball of twine right at the end, letting all the tension unravel in seconds.