A young couple, Angus and Caroline Jenson, hold a seance to contact their recently-deceased son. Something goes wrong and Angus is thrown against the wall by a powerful spirit. When he starts to experience blackouts and has a vision of a car plunging into the water, he visits the Department of Parapsychology at Clyde for counsel. As he becomes increasingly violent, the team races to determine who or what has possessed him.

Believing that a scarf has set off a premonition of a local woman's death, Justine tries to locate her to prevent the terrifying vision from coming true.

Justine agrees to help one of the students in her tutor group with a research project involving monitoring the girl's boyfriend's sleep patterns. The boyfriend, Stuart, has been suffering from lack of sleep due to terrible nightmares. Stuart's dreams seem to be able to manifest in the physical world, and Justine along with Stuart, his girlfriend Chloe and another friend, begin to experience some unsettling manifestations - including a room full of moths. Dr. Monaghan arrives to help, but the group find themselves trapped in the university. Unable to wake Stuart, they must try to work out what is causing the manifestations before it is too late.

Justine and Craig are hired by Rosie Galt, the manager of an upmarket hotel. She wants them to prove that the hotel is not, as many are beginning to suspect, haunted. The duo are suspect that the job will be a waste of their time, but soon experience strange phenomena: flashing lights, wierd noises, extreme temperature drops and ominous broadcasts on the TV. Could the phenomena be caused by the Rosie's jealous brother, who wants to wrest control of the hotel from his sister, or could they be connected to the newsroom that used to occupy part of the hotel's premises? If it is a genuine haunting, what is behind it?

A young man is approached by lady who predicts his death, handing him a card bearing a drawing of a strange owl-like creature. He approaches the department, but Craig and Justine are sceptical. When he dies soon after his visit, the pair begin an investigation. Justine follows up the drawing, while Craig checks out a business card for an escort agency that was left in the man's jacket. When he tries to log on to the agency's website his computer crashes but shortly afterwards he is approached by a beautiful woman claiming to be from the agency, who begins to seduce him. Although she does not tell him who she is, she is the dead man's fiancee. Meanwhile Justine's investigations suggest that the man's death may have been the work of a succubus - a demon that seduces men to produce more succubi, killing those who do not successfully impregnate them. When Craig is hit by a mystery illness, it appears that he might be the succubus' next victim...

After dabbling in black magic, a young woman manifests extraordinary electrical phenomena. Monaghan and the team find themselves in a race to understand and fight the dark forces attacking her before it is too late. The season finale to series three.