Professor Matt Hunter is an atheist ex-minister and expert on religion, brought in by the police to advise on cases where there is a supernatural overtone. When they receive a report of strange whispers behind a blood-soaked door, they are baffled to discover a man, who will only speak in whispers under his breath, with the name Baal-barith tattooed on his chest. They have no choice but to call in Matt Hunter. Matt knows that Baal-barith is an ancient Canaanite demon and was known as the spirit of "blasphemy and murder". But as more "demons" appear around the city, the police and Matt must work quickly to find out what is behind this extraordinary situation.