Season 1

In order to interest a television mogul in buying his stories for the small screen, novelist and adventurer Jason King describes to the man a typical plot involving his hero, Mark Caine. Caine meets a girl who has been given plastic surgery to resemble the deceased Michele who died in a fire. She is taken by two crooks to meet Bellini, a fence of Michele's acquaintance, supposedly suffering from amnesia, to find out where he has hidden his private stash of valuables. Caine is aware that the girl will be killed once she has served her purpose and steps in to rescue her.

British Intelligence plan to copy the plot of Jason's book, 'A Page Before Dying', to smuggle Gorini, a man who has information for them, out of East Berlin hidden in a safe. The first part of the scheme involves Jason being smuggled into the East in the safe, but when he reaches the meeting place, he finds that he has been duped and used as a decoy, whilst Gorini has already been taken to safety through other means.

Jason needs to finish his latest book, so he decides to go into isolation in the south of France. When he picks up a pretty hitchhiker and a recently released prisoner, it becomes the start of yet another Jason King novel.

On a visit back to England, Jason finds himself with income tax problems. However, it turns out to be a way of blackmailing him into helping the police solve a series of robberies where the police computer seems to be illegally accessed.

A close friend of Jason King, a double agent called Alan Keeble, was supposed to be dead. However, when Jason receives a letter telling him to come to Vienna to meet Alan, he just has to go.

Two English criminals, Charles and Edward, are committing copy-cat robberies stolen from the plots of Jason's books, which causes the police to take an interest in the author after a security guard is killed. Jason and his girlfriend Arlene, have an encounter with the two villains and escape but, as they can now recognize the pair, they are in danger as they head for Venice, where a trap has been set for them.

Jason is abducted in order to help the Moscow police work out how three men on a workers' delegation, got into a lift and then, when the doors opened again, there was nothing left of them but three piles of ashes. He discovers that they made their exit from the lift by means of a trap door, but comes to appreciate that they are part of a larger plan to tunnel into the Kremlin to steal art treasures.

Jason is mistaken as a hit man when he is left holding a bunch of roses at a Swiss airport after coming to the aid of a seriously ill man. To Jason's horror, the roses are soon to be exchanged for a rifle!

An antique salt cellar made of gold by Benevenuto Cellini is stolen in California from collector Dreshfield by thief Frankie Luca, who brings it to Paris to sell to Philippe De Brion. De Brion was cheated out of its ownership some years earlier by Dreshfield, who told him it was worthless. However free-lancer Mallen has been hired by Dreshfield to pursue Luca to Paris, where he meets up with Jason, and asks him to introduce him to De Brion. After Mallen has been shot at, he and Jason track down the salt cellar, only to find that it is a fake and Luca has escaped with the real one.

Having killed De Brion, who was out to double-cross him, Luca gets on a train to Rome with the Cellini salt cellar, pursued by Jason and Mallen. In Italy a former Mafioso called Angelo Andrea, joins the chase, intending to steal the Cellini from Luca. Ultimately all the interested parties end up at Andrea's house, where they discover that all that glisters is not gold.

Jason arrives on a Caribbean island and find himself in the middle of a revolution when he inadvertently makes a remark about flamingos.

In France, Jason meets Toki, whose boyfriend Jean Le Grand and another gangster, Olivier, plan to steal a cache of emeralds — after which Le Grand plans to kill Olivier. Given that she knows all the plans, Jason believes that she is a young girl who has got out of her depth and is in danger. He resolves to help her, but they are pursued by LeGrand and his mobsters.

Jason falls under the hypnotic spell of two glamorous thieves, Claudia and Elaine. Claudia steals from him the only copy of his recently completed film script, and she and Elaine demand that, for its return, he pose as an expert in ancient manuscripts in order to steal the Constance Missal, a valuable document recently acquired by the British Museum. He is to authenticate it for one Lord Barnes, but his lordship is also planning to obtain the Constance Missal for himself.

Having refused to help the British government investigate an international drugs ring, Jason is surprised to learn that a man in Istanbul is impersonating him. This turns out to be Trim, a government operative, who has been studying him in order to make contact with the gang leaders and persuade then that he is Jason King. However, Trim is captured and Jason has to go to Istanbul after all, to save the day.

Jason is suffering writer's block, so his publisher sends him to Greece to inspire him. However, some Greek criminals use a beautiful woman to seduce Jason, using his fame to smuggle drugs into France — but who is seducing who?

Jason travels to a South American republic to receive an award — in the form of a medallion — for one of his books. In fact, both the corrupt President Cordoba, who has bugged the medallion, and the opposing rebel forces, led by glamorous government minister Delphi, believe that the book is so close to the truth about events in their country that Jason has an actual source of information. Neither will believe that the book is all fiction.

Jason's temporary secretary in Germany convinces him to go to a health clinic. However, when several strange events occur, he realises that there is much more to the clinic than it appears.

Jason is in Paris taking publicity photos for his latest novel, when a man with a rifle shoots at him. It appears that there is bounty of 100,000 francs on him, but who is putting up the money and why? King has to find out.

Andrew Bishop is a nasty piece of work, who lives with — and makes life unpleasant for — his elderly, housebound Aunt Claire. One day, in the process of robbing a house, he commits a murder, for which Pamela, an innocent woman, is charged. He also steals a vacuum cleaner which, somewhat bizarrely, is Jason's chief clue in leading him to the real culprit.

Arriving in Venice, Jason is surprised to learn that he is the apparent author of a book entitled 'The Stones of Venice', which he assuredly is not. However, after he is attacked by two would-be assassins, a jewel robbery takes place, and Theresa Bonival, employee of a firm specializing in antique jewellery, is abducted. These incidents are closely related to events in Jason's book, and therefore sufficient for the police to ask for his help in their inquiries.

A mysterious girl calling herself Karen, invites Jason to meet her at the Capri hotel, but when he gets there he finds a note requesting he catches up with her at a night-club. He meets up with her, but an apparent drunk drops a lighter into his pocket. Then Karen takes him to meet a lady who may or may not be a princess, and who has a proposition for him.

Jason makes a stopover in Hong Kong, where his character Mark Caine appears in a Chinese comic strip — but with deliberate alterations to Jason's original story in the translation. He teams up with Lucy Cameron, nurse to wealthy businessman Arthur Tsung, to confront Irish-American Sam Finnigin, the editor of the paper publishing the strip and a man whom he has met before, for an explanation.

Jason King arrives in Rome just after a night-club dancer is murdered. When he finds out that the events in the book he is currently writing, mirror what is happening in real-life, Jason is determined to find out what is going on.

Whilst travelling on a plane, Jason recognizes a man whom he knew from his Department 'S' days to be a professional assassin, and so he is intrigued and on his guard when he arrives at his destination. But, not without due cause, as he will soon find himself caught up in a plot to foil a group of revolutionaries out to kidnap the daughter of the country's president.

In London, Jason is paid a great deal of money for a film script, only to be relieved of it by two robbers. Later, whilst taking a moonlight stroll he sees an astronaut shooting somebody, and then he is attacked and knocked unconscious by a bear. When he wakes up next morning with a headache it all seems very real, but the police obviously believe that he dreamed it.

Jason has an invitation to go to Italy and stay with Bonisalvi, an international criminal who lives in the most secure seclusion. A rival gangsters' syndicate uses the opportunity to send Bennett, a hit-man posing as Jason to kill Bonisalvi. Meanwhile, Jason himself has problems fleeing the beautiful but deadly Martine, who seems to have more than marriage on her mind.