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.

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