Set in the 1900s, when the British Secret Service was a new, unofficial arm of military activity, the series features Captain Robert Virgin - an officer and a gentleman who fights as a man of honour. Armed only with intelligence, ingenuity, physical strength and abundant charm, Virgin faces every sort of peril as he defends King and country - from industrial espionage to anarchist bomb plots, assassination attempts to kidnapping.

The evil crime syndicate Thanatos is bent on taking over the world, using a magnetic wave generator that will cause all metal-based machinery to grind to a halt. However, the well-known British secret agent normally assigned to such tasks isn't available, so they engage his civilian brother, Neil, to help. Neil, played by Neil Connery, is a world-class plastic surgeon, hypnotist, and lip-reader, which turn out to be precisely the skills required for thwarting Thanatos.