Miriam promises her lovers the gift of eternal life, but John, her companion for centuries, suddenly discovers that he is getting old minute by minute, so he looks for Dr. Sarah Roberts, a researcher on the mechanisms of aging, and asks her for help.
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.