Crippled mastermind Mario Orlandi di Alsconi, who is motivated by misanthropy, sets up a gang of blackmailers. His henchmen kill unscrupulous and without any hesitation everyone who is not ready to pay the sum demanded by the gang. English student Donald "Don" Micklem wants to avenge the murder of his uncle. Almost by himself he manages to break up the blackmailer ring and to bring Mario Orlandi to his just punishment.