When Students Alex and Patricia (David Ladd and Sharon Gurney) discover a dying man in their local underground station, they spark off an investigation that reveals a sinister and macabre plot that even turns the stomachs of hardened police officers Calhoun and Rogers (Donald Pleasence and Norman Rossington).Prominent people, it seems, have been disappearing from London tube stations, and an MI5 agent (Christopher Lee) is called to help solve the deepening mystery. What is the terrible secret of the capital's underground system? And who - or what - is turning tube tunnel into a Death Line?, When Students Alex and Patricia (David Ladd and Sharon Gurney) discover a dying man in their local underground station, they spark off an investigation that reveals a sinister and macabre plot that even turns the stomachs of hardened police officers Calhoun and Rogers (Donald Pleasence and Norman Rossington).Prominent people, it seems, have been disappearing from London tube stations, and an MI5 age