Samantha (Heather Graham) and Craig Howard (James Purefoy) are desperate to have a baby, but are having trouble conceiving. They seek help at a peculiar new fertility clinic, and Samantha becomes pregnant. But the couple are then approached by the unhinged Father Carlo (Andy Serkis), who claims Heather is carrying twins spawned from the Devil's DNA, and the clinic is really a front for a satanic cult that plans to use the Howards' children to take over the world.