Richard Johnson's search brings him among other places to Northern Ireland, where he meets a jeweller in Belfast who called in an exorcist to save her business, and interviews a doctor who believes exorcism can cure cancer.

But some episodes of uncontrolled deliverance can mean that exorcism becomes a serious, even fatal, matter.

A clinical psychiatrist explains how typical psychotic symptoms of schizophrenia and bipolar disorder such as hallucinations, hearing voices or depression can look like demonic possession.

To confuse matters further, schizophrenics often think they are having a spiritual experience.

Are doctors and psychiatrists the new exorcists?

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	Programme Four Of Exorcism