 "Blood Relatives" was filmed under a policy that allowed full tax deferment to foreign produced films if they reflected a specific portrait of Canada.For this reason, the novel's setting of a thinly-veiled New York City is changed to Montreal.One rainy night a teenage girl called Patricia staggers wounded into a police station saying that she and her older cousin Muriel, who lived in her family home, had been brutally attacked with a knife in a dark alley.