When Liz Kirkland marries archaeologist Alec Graham after a whirlwind romance, she little realises the part she will play in his attempts to bring his arch enemy to justice. The death of Alec's friend, the actor Andrew Ferry, leads her into the dangerous world of the psychic organisation P.S.I. and the demonic powers at its heart. Will she destroy the evil there before it can destroy her? This story of revenge is set against a backdrop of occultism and the paranormal in 1970s London.