The film opens as a pregnant woman (Danielle Cormack) gives birth to a vampire. A young Brother, Silus, aged 10-13 is told this child, Edgar and he are from the same mother. Throughout this introduction, the mother is in visible emotional distress, reaching out across the room to Silus, trying to touch him.
Captioned "100 Years Later." Jamestown slum has had a series of attacks on women, who are all found with their throats bitten. Lilly Squires (Saffron Burrows) is in charge of the human police investigating these cases. She states that she comes from a workhouse in this same slum, and we establish that she is one of the few cops who care what happens to these people at the bottom of the socioeconomic heap. Lilly finds a small boy who witnesses one attack, and tells her that a Brother was responsible. As the police don't want to panic the city, the string of murders is explained away as being the result of an outbreak of the rampant influenza virus.
Silus (Dougray Scott) is detailed by the church cardinals to work with the human police, because the Brothers know that these attacks have been carried out by a Brother; Silus's brother Edgar (Leo Gregory). Edgar has sent Silus a recording of his last murder, challenging him to find and stop him before he kills again. Edgar provides the location of his next murder.
With Silus' help, Lilly puts together a task force to stake out the area Edgar has targeted. However Edgar distracts the cops and attacks Lilly, biting her in the neck. An officer interrupts the attack and Edgar flees. To save Lilly's life, Silus tells her to drink his blood, which she does. Silus then pursues Edgar, managing to shoot him with a tranquilizing dart. Silus later visits Lilly in hospital. We establish that she has no family as they died from influenza. Lilly is having visions from drinking Silus' blood. The newspapers have published a fake story of the death of the killer; a deranged human who believed he was a Brother.
Edgar is being held in a "brace", a spiked body restraint in a cell in the church basement. Because Silus is soon to be made a member of the "inner circle" he is told the full details of what happened to Edgar. The cardinals are worried that not a single Brother has been born for 70 years, and that a female vampire has never been born. Although they have publicly banned genetic research, the church has been carrying it out in secret. Edgar has been developing a virus to inject into pregnant women, to force the baby to be born a vampire. Alas the virus has mutated, and it has turned the women into violent, insane, psychopaths. Ten of Edgar's research subjects are already dead, and the last one is dying. Edgar has also become infected, and is now insane, although the effect is slower due to his strong immune system.
Silus visits Edgar, who vows to escape and finish off Lilly. Edgar accuses Silus of being in love with Lilly, despite Brothers being forbidden to love. The night Silus is at a ceremony in the church for his investiture as a cardinal Edgar escapes, killing the guards and receptionist, and disappears into Jamestown. He enlists the help of a local named Freddy to help him catch Lilly. Edgar has installed a tap and tube system into his forearm, so he can turn on a flow of his own infected blood at any time. He catches a policewoman and fills her mouth with his blood. Freddy insists on getting his own share as well, not knowing it is infected.
