The police now view the case as murder and Lynn is their prime suspect but as the homicide cops point out to Cam it’s incredibly difficult to get a conviction in a poisoning case. And sure enough, Polly is found to have died from a massive dose of strychnine. They feel so uneasy that they persuade the police medical examiner to perform an autopsy. Of course they all realise that this is just wild supposition but they can’t help feeling slightly uneasy, especially when Cam mentions that Lynn was anxious to have Polly cremated although he’d managed to talk her out of it. After their father’s death he was the closest thing they had to a father and being childless himself the two children were the closest thing he had to a family. So Lynn would in fact have a motive for murdering Polly, and she’d also have a motive for murdering the surviving child, Doug. And the estate is a very substantial one indeed. But if both children were to die Lynn would get everything. Of course there’s probably nothing in it, but still it is odd.Īnd then Fred (Gary Merrill) mentions that he had prepared Cam’s brother’s will and that all the money was left in trust to the children. And Polly’s father’s symptoms just before he died were very much the same. What bothers Maggie is that Polly’s symptoms, although they could be explained by a number of illnesses, do just happen to be the symptoms of strychnine poisoning. Maggie (Catherine McLeod) is a pulp writer and some time earlier she’d been doing research on poisons for a murder mystery. So far it seems like just a straightforward family tragedy and that’s what Cam assumes it to be until he starts talking to his friends Fred and Maggie Sargent. Their mother died many years earlier but the brother’s second wife Lynn (Jean Peters) raised the children as her own. Polly and her brother Doug were the children of Cam’s brother who died some years earlier. She soon seems to be on the road to recovery but then has an equally unexplained relapse and dies. She keeps screaming to the nurses not to touch her feet. His niece Polly has suddenly been stricken by a mysterious illness. Whitney 'Cam' Cameron (Joseph Cotten) rushes to the hospital to be with his sister-in-law. It’s well-made but it’s biggest asset is the excellent cast. A Blueprint for Murder is a rather superior 1953 20th Century-Fox murder mystery with just a dash of film noir to it.