Chiller - Season 1 Episode 5 Number Six

In a small Yorkshire town, Detective Inspector Jack Taylor tries desperately to find the child murderer who strikes when it is full moon. After five murders, the town dreads number six. A psychiatrist examines the drawings of local school children and discovers an important clue. When Taylor uncovers a connection to an ancient Druidic site and thinks he has discovered the murderer's identity, he realises that the next victim-to-be is his own son.