London’s walls resound with the incredible exploits of the “Yellow Mark.” The spectacular actions of this mysterious criminal are on the increase: holding up the Bank of England, robbing the imperial crown... No one seems able to stop him. He is so audacious that he lets the police know in advance where he will commit his crimes, each time ridiculing Scotland Yard a little more. The apparent ease with which he evades police schemes begins to worry the highest authorities of the country. The Home Office asks Captain Francis Blake to solve the mystery and discover the identity of the man who hides behind the Yellow Mark. The captain immediately takes as partner his old friend, Professor Philip Mortimer, whose scientific knowledge will be invaluable in solving this extremely complex enigma. Who hides behind the Yellow Mark?

Professor Philip Mortimer has decided to spend his holidays in Cairo with his trusty servant, Nasir. There he plans to meet his old friend, Professor Ahmed Rassim Bey, who offers him the fantastic opportunity of satisfying his passion for Egyptology. Professor Bey has invited him to take part in deciphering his latest discoveries—in this case, some papyrus coming from mummies of the Ptolemaic age. Mortimer and Bey soon realize that one of the fragments deals with the “Chamber of Horus,” a fabled crypt that could contain priceless treasures...

Captain Blake having been assassinated at Athens Airport, Olrik seems to have won the first round. A furious Mortimer swears that he’ll never stop trying to avenge his friend. He goes on the hunt for Olrik, but information is scarce. Sheik Abdel Razek, an old man with mysterious powers, protects him against Doctor Grossgrabenstein’s crew. The doctor is a devoted Egyptologist who has undertaken excavations not far from the Great Pyramid. Strange happenings occur and Mortimer may sometimes feel like he’s losing his way in this investigation that will lead him into the darkest depths of the Great Pyramid.

Scandal breaks in the London press: There is a mole in the Intelligence Service! And it appears without a doubt, on a photograph taken by agents of MI 5, that the mole wears the face of Francis Blake! Mortimer is determined to believe that his friend has been forced to act against his will. But the initial investigations sweep away this hypothesis: Blake has opened, under an assumed name, an account fed by payments coming from the Bahamas. In a few months, he has withdrawn ₤30,000—more than 10 times his annual pay! With MI 5 agents planning to try Blake for high treason, or to kill him if needed, Mortimer decides to find his friend before they do. A long hunt begins …

Blake and Mortimer head to the United States to investigate the mysterious circumstances surrounding the discovery of a 177-year-old body, which appears to have died very recently. The body is that of a Scottish major, Mortimer’s forebear, who was leading a British military expedition to the US in 1777, where he was swallowed up by a strange multi-coloured light-beam shining down from the sky. Blake and Mortimer fight men in black armed with green-laser guns and soldiers emerging from the past in order to save the Earth from complete obliteration.

Extreme weather threatens the whole of continental Europe, turning the lives of its citizens inside out. The French government calls Professor Mortimer to help solve this enigma. Mortimer travels near Paris to visit his friend Professor Labrousse, the chief French meteorologist. But when the taxi driver Labrousse sent to meet Mortimer at the station disappears, our friend becomes the prime suspect. Mortimer gets in touch with his old friend Blake, also in France, to help him out of this tricky situation. However, Blake disappears as well, so Mortimer and Labrousse have two missing-person cases to investigate. They soon discover that the two disappearances are not only linked to each other, but also to the climatic catastrophes.

A necklace that used to belong to Marie Antoinette, the last French queen before the French Revolution, turns up in the hands of a British collector who decides to present it to Queen Elizabeth. Blake and Mortimer’s sworn enemy Olrik, about to be tried in Paris, manages to escape and steals the precious piece of jewellery in front of their very noses during a glittering reception in the French capital. The affair threatens to turn into a full-blown diplomatic incident, especially since Olrik is doing his best to embarrass Blake and Mortimer by tipping off the press about his every move.

A Soviet rocket falls back to Earth carrying deadly bacteria. KGB Professor Voronov turns the extraterrestrial threat into a terrifying weapon that could be used to devastate the Western world–but he doesn’t take into account the vigilance of Her Majesty’s intelligence services. Soon, Blake and Mortimer are drawn into a lethal, shadowy war, from Moscow to London, where the stakes are no less than international peace and the real enemy may not be so obvious.

Philip Mortimer spent his youth in the land of the Maharajas. He loves India, but his last visit there did not end well. Now, many years later, the famous Professor Mortimer is in charge of the British pavilion at the Brussels Universal Exposition. When strange phenomena begin disrupting preparations, Mortimer and his friend Blake set off on a trail that will take them to the sixth continent—to confront an old and unexpected enemy.

Blake, Mortimer and Nasir are en route to Antarctica, hoping to locate Olrik and his Indian and KGB allies and to stop his attack on the Brussels Universal Exposition. Little do they know that their old adversary isn’t the one in charge this time. In the frozen wasteland of the sixth continent, Mortimer will be reunited with an old acquaintance and solve the enigma of his younger days—at a terrible price.

Several months after their adventures in Antarctica, Blake and Mortimer are back in England. Still somewhat shaken after his ordeal, the professor is ordered by his doctor to get some rest. In typical Mortimer fashion, he decides to spend his holidays in Africa… looking for a lost civilisation! Accompanied by Nastasia Wardynska and an old flame of his, he begins tracking down a culture that is older than any ever recorded—but someone is dogging their every step…

Deep under Sao Miguel island, rumoured to be the last emerging part of Atlantis, Professor Mortimer has discovered samples of a mysterious radioactive metal. Could it be the Atlanteans’ legendary orichalcum? When he and his friend Blake set out on an expedition into the depths to find out, sabotage occurs in the form of their old opponent Olrik. And soon, all three will be embroiled in a power struggle far bigger in scope than they could have imagined.

In Pennsylvania, Olrik escapes a federal prison by helicopter after a bloody attack. With Blake forced to cut short his holidays at the news, a disappointed Mortimer turns his attention to Greece, where an earthquake has uncovered an ancient chapel. Before long, people are trying to kill Mortimer over a mysterious Roman silver coin. Could the long-lost relic be one of the 30 denarii paid to Judas for his betrayal of Jesus? And who exactly covets it so much?

Captured and then abandoned by Olrik, Mortimer is now lost at sea with no provisions. Fortunately, he can always count on Blake. Once reunited, and with the help of some old friends, the two British gentlemen continue their dangerous mission to stop Von Stahl from resurrecting the Third Reich using the evil power of the 30 pieces of silver… a mission that will take them throughout Greece and into the very Kingdom of Hades!

In a past almost, but not entirely, like ours, the world lives in dread of a new power, an empire centred in Tibet and led by a megalomaniac. When the inevitable attack comes, it destroys all opposition, and capital cities across the planet are left burning. But, in Great Britain, Professor Mortimer, inventor of a mysterious weapon named the Swordfish, and his friend and protector Captain Blake, have escaped the destruction, and must make their way to a secret base...

Fleeing the devastation of World War III, Blake, Mortimer and Nasir have been trying to reach a secret base with the blueprints for a new weapon, the Swordfish. But the forces of the Yellow Empire are hot on their trail, and soon Mortimer is captured. While Blake works tirelessly at coordinating the various resistance movements on the planet, the professor is forced to endure captivity, threats and torture from their eternal enemy, Olrik.

The captain and the professor have finally made it to the secret base with the Swordfish blueprints, and construction has begun on the extraordinary machines. Olrik hasn’t had his last word, though, and he is ready to take tremendous risks to locate the world’s last bastion of resistance and freedom. A race against time is on between Imperial forces on one side and Mortimer’s teams of engineers on the other... The fate of civilisation is at stake.

1919. Colonel Lawrence – Lawrence of Arabia – has an unpleasant meeting with an MI5 agent who confiscates his manuscript of The Seven Pillars of Wisdom. 35 years later, Oxford is shaken by a series of burglaries at the Ashmolean Museum, at the same time as Blake learns of the death of an old friend. The captain begins an investigation, while Mortimer looks into the thefts… But what dark connection does all of this have with Lawrence or Blake’s own past?

Professor Mortimer is bequeathed an old house in France by a former adversary: Miloch, the evil genius of SOS Meteors fame. Along with the house is a letter inviting the Briton, as the only man of worthy intellect, to discover a fabulous invention left behind by the departed. Following recorded instructions, Mortimer activates the device … and wakes up a hundred million years in the past! Thus begins an incredible odyssey through time…

It’s been several months since the events of The Yellow M, but the evil of Professor Septimus still echoes around London. Important figures of the capital’s jet set come together around the questionable values the mad scientist defended. Olrik is forced to resort to opium in order to forget he was guinea pig. As for Mortimer, he too is trying, albeit for more humanist reasons, to revive certain aspects of Septimus’s work – to Blake’s extreme concern…