A mysterious artifact unearthed below a London Underground station proves to have powerful psychic effects on the people around.
There's something pretty grisly going on under London in the Tube tunnels between Holborn and Russell Square. When a top civil servant becomes the latest to disappear down there Scotland Yard start to take the matter seriously. Helping them are a young couple who get nearer to the horrors underground than they would wish.
A Scotland Yard detective is investigating a string of robberies and a murder, and the information he uncovers leads him to the estate of a wealthy but strange English family, who share their mansion with a group of nuns. The detective comes to suspect that neither the family nor the nuns is quite what they seem to be.
