A strangler is loose on a British estate, and he not only strangles his victims but brands an "M" onto their foreheads before he decapitates them.

Then the spirit of Jack the Ripper seems to be very much alive in 1960s London as a series of brutal slayings by the Monster of London City has Scotland Yard baffled. In a macabre coincidence, a new play about the famous murderer is about to become a major West End hit... and the leading man is rapidly becoming the prime suspect!

A series of knife murders have an odd feature about them; the victims find that their luggage has been packed for them just before their deaths. Scotland Yard investigates, and discover that the murders are linked to an addictive drug called Mescadrine.