When psychology lecturer and psychic mediums specialist Robert Bridge takes his students to a clairvoyance evening, he meets troubled psychic Alison Mundy. Sceptical about her abilities, Robert decides to study Alison and contemplates writing a book about her after sitting in on one of her readings. But he is completely thrown when Alison claims to see the spirit of his dead son Josh.

An eight-year-old girl goes missing and her distraught parents make an emotional televised appeal. The next day, when Alison says she has seen the child's ghost in the supermarket, the police are deeply suspicious - then they discover a drowned body.

On the ward of a hospital psychiatric unit, Alison meets Daniel, who is being held after an attack on his girlfriend. He desperately tries to persuade Alison that the man responsible for the assault was the other Daniel - Daniel Two. Doctors are convinced the young man is a pathologically violent schizophrenic, but Alison has serious doubts.

On the first day of her new job at an old people's home, Alison finds a photo of Robert's dead son Josh, belonging to his mother, Jenny, and realises that Josh steered her towards the job in another attempt to make some kind of emotional contact with his father. Alison befriends fellow nurse Connor, who is being tormented by the ghost of a former patient, who jumped to her death from a window because he wouldn't help her die peacefully.

Sandra Petch is petrified and thinks that her flat is haunted, but when Alison comes round to try and help she witnesses the terrifying tableau of a man smothering his wife to death. Robert is curious and the three spend the night there, waiting to see what will happen. As Alison falls asleep, she enters a nightmare where she relives the last moments of the murdered woman's life.

Alison thinks that she is being haunted by the victims of the train crash which nearly killed her six years before. But she soon finds out that she is being followed by the survivors of the disaster, who want her to help them communicate with their lost loved ones. Robert and she come into contact with the afterlife in a way that will change their lives for ever.