As Mary and her teenage son, Fergal, move to yet another new home, it becomes clear that they are living their lives on the run, hiding from someone or something, terrified of being found. Trying, as usual, to make new friends wherever they find themselves, Fergal wins the affections of a beautiful and feisty neighbour. But his fiercely protective mother, suspicious of everyone and everything, will stop at nothing to protect her precious son.
Their pursuer is Cathal, dangerous and terrifying, and apparently intent on tracking down and killing both Mary and Fergal. Their fear mounts as local residents fall victim to a series of brutal murders, believed to be committed by some kind of inhuman creature. Is Cathal the beast responsible for the killings? Or is Cathal not what he seems, and actually trying to destroy the beast?