Rob and Karen Catto are a newly married young couple settling into their lives together on the northeast coast of Scotland. Rob's job as a janitor at the local school involves him in both the lives of his students and issues of security. So he takes sharp notice of a hulking figure in a parka lurking around the edges of the school, leering through windows, and squatting in an abandoned concrete bunker. As unpleasant and unsettling incidents multiply,...