A serial killer calling himself 'The Marquis' has been murdering celebrities, and Scotland Yard is baffled. On meeting a young private detective named Rita Cartwright, Paul Temple discovers that she has been running her own investigation into the murders, and believes they are linked to a gang of cocaine traffickers. The next day, Rita is found dead, with a square of white card pinned to her dress signed 'The Marquis'. Paul finds himself up against a malevolent criminal mastermind who always seems to be one step ahead.