London 1972. Are ghosts really haunting Hampton Court Palace? Dr. Simon Carlisle is commanded to find out The Queen's Gallery at Hampton Court Palace is known as the 'Haunted' Gallery. Two visitors collapse there during a guided tour. One dies shortly afterwards, and the other remains too ill to describe what happened, until she commits suicide. A royal courtier is commanded to solve the problem. Sir Edmund Pemberley engages a young consultant psychiatrist who is researching the paranormal to investigate. He doubts that he will discover anything abnormal but, with his technician, Adrian, Simon Carlisle set up vigils in the gallery. Alice Charrington, the historical archivist to the royal palaces, is assigned to help - and Simon begins to fall in love. During the vigils they discover not only the ghost of a distraught young woman in Tudor dress, but must also confront an elemental force of evil - satanists are using the Palace. Abbot Assuntino Ginanneschi, from the Vatican, attempts an exorcism, but Alice is possessed then kidnapped. The Abbot, Professor Hutchinson, Simon, Adrian and Adrian's girlfriend, are a pitifully small force to confront the Satanists. and Simon's race to save Alice becomes an epic struggle between good and evil.
Inexperienced ghost hunters and the Vatican's most experienced exorcist are pitted against ruthless Satanists led by a psychopath with only one ambition...will good prevail?