When a government official disappears in the London tunnels, after several reports of missing people in the same location, Scotland Yard start to take the matter seriously, along with a couple who stumble into a victim by accident.

• Harbor Ventures
• K-L Productions
• Donald Pleasence
• Norman Rossington
• David Ladd
• Sharon Gurney
• Hugh Armstrong
• June Turner
• Clive Swift
• James Cossins