A cautionary admission to the police, by Arlette, a burlesque dancer, warns of the murder of a countess- but is is Arlette who is strangled before a countess is also reported murdered. Maigret, assisted by a new recruit, methodically trails and tabs the unknown man who had figured in both lives..... A thinning plot line, for which Montmartre provides a montage of seedy to shady characters.