Mourning the death of his fellow agent and friend Nick Craig, Miller, and new GS5 operator Peter Clarke, are sent to check out explosion at sea. Their investigations bring surprising - and to Miller - highly satisfactory results.
Masquerading as a news reporter, Tony Miller investigates the death of a policeman suspected of being 'on the take' from gamblers. His search for the cop killer leads him into the world of high finance.
Assigned to investigate a series of sabotage incidents involving a new machine being designed for South America. Clarke 'defects' to the Fascist party responsible for the crime - with dangerous results.
GS5 operative Tony Miller finds himself facing a tough problem: how could a man be seen driving a car though a village and yet, when the vehicle crashed, the man is found to have been dead for several hours?
When a protection racket gang declare war on innocent people, GS5 agent Tony Miller is assigned to infiltrate the gang and force the opposing sides into a showdown. He achieves this - with startling results.
Stock's disbelief that a 'master criminal' is behind a series of brilliantly executed robberies is severely shaken when operative Peter Clarke brings him conclusive proof that successful criminal Dr Ayre is masterminding further audacious crimes.
The island of Baleric hides a sinister secret which GS5 operator Tony Miller must solve if he is to have any chance of locating the whereabouts of a fellow undercover agent believed kidnapped by director Zafre.
Sent to check out the strange goings on at a secret missile base. GS5 operatives Clarke and Miller find their cover blown and the enemy awaiting their arrival - a dangerous situation when you're seeking a sadistic killer.
Stock assigns his entire department to locate Franz Rodolph Gruber, a former Nazi chief in Hungary. Gruber is known to have in his possession the Howarth jewel collection - which Stock suspects will be used to finance a new Nazi regime.
Undercover operative Sally Lomax is assigned to delve into the past of a man whom Stock believes to be a murder. The man, Dawson, is new managing a holiday camp - at which several 'accidents' have taken place. Sally books in - but her holiday is far from peaceful.
After a whirlwind courtship on the French Riviera, GS5 agent, Peter Clarke, posing as a shy businessman, 'marries' Yoette, an attractive French girl - in order to discover the secret behind another French girl's mysterious death.