On the plane Tintin begins to suspect his companion. The Alembick travelling with him doesn't smoke and doesn't seem to need the spectacles he wears, while the Alembick he first met smoked heavily and had very poor eyesight. During a layover, Tintin fakes a fall and grabs Alembick's beard, thinking it is false and Alembick is an imposter. However, it is (for Alembick) painfully real. Tintin decides to let the matter drop but then, while flying over Syldavia, it is the pilot of the plane who opens a trap door and Tintin drops out, landing in a haywagon.
Tintin has a hunch that a plot is afoot to steal the sceptre of King Ottokar IV. In Syldavia, the reigning King must possess the sceptre to rule or he will be forced to abdicate. Every year he rides in a parade during St. Vladimir's Day carrying it, while the people sing the national anthem. Tintin succeeds in warning the reigning King, Muskar XII, despite the efforts of the conspirators. He and the King rush to the royal treasure room to find Alembick, the royal photographer and some guards unconscious and the sceptre missing.
Tintin's friends Thomson and Thompson are summoned to investigate but their theory on how the sceptre was stolen proves bad and painful for them. Later on, Tintin notices a spring cannon in a toy shop and this gives him the clue. Professor Alembick had asked for some photographs to be taken of the sceptre, but the camera was a spring cannon in disguise, which allowed him to catapult it out of the castle into a nearby forest.
Searching the forest, Tintin spots the sceptre being found by agents of the neighbouring country, Borduria. Following them all the way to the border, he wrests the sceptre from them. In the wallet of one of the thieves he discovers papers that show that the theft of the sceptre was just part of a major plan for the taking over of Syldavia by their long-time political rival, Borduria.
Tintin steals a Me-109 from a Bordurian airfield (whose squadron is being kept ready to take part in the envisioned "Anschluss" of Syldavia) to fly it back to the King in time. He is shot down by the Syldavians who have naturally opened fire on an enemy aircraft violating their airspace. He manages to make the rest of the journey by foot.
Meanwhile the Interior Minister informs the King that rumours have been spreading that the sceptre has been stolen and that there have been riots against local Bordurian businesses, acts which would justify a Bordurian takeover of the country. The King is about to abdicate when Snowy runs in with the sceptre (which had fallen out of Tintin's pocket).
Tintin then gives the King the papers he took from the man who stole the sceptre. They prove that the plot was masterminded by Müsstler, leader of the Iron Guard, a local political party. The King takes action by having Müsstler and his associates arrested and the army mobilised along the Bordurian frontier. In response, the Bordurian leader pulls his own troops back from the border, though he stresses his own country's "desire for peace" and criticises Syldavia's "strange" behaviour.
The next day is St. Vladimir's Day and Tintin is made a Knight of the Order of the Golden Pelican, the first non-Syldavian to receive such an honour. Further inquiries by the authorities reveal that, in a classic Ruritanian plot device, Professor Alembick is one of a pair of identical twins: Hector Alembick was kidnapped and replaced with his brother Alfred who left for Syldavia in his place.
Tintin and Snowy return home by a flying boat with Thomson and Thompson, who suffer momentary panic when the aircraft appears to be falling into the sea at the end of the flight. The reader is treated to a rare "wink to the camera" from Tintin, who points out their error, and they laugh about it so much that they do indeed fall into the sea as they disembark.
Müsstler is the head of the Iron Guard. The name implies that it is a pro-fascist paramilitary group similar to the SA or Blackshirts which were common in Europe between the wars. An actual group called the Iron Guard was active in Romania in the years leading up to the Second World War.
However, these parallels appear to have been lost on the German censors during the occupation of Belgium during World War II; while Tintin in America and The Black Island were banned because they took place in enemy countries like the United States and Britain, King Ottokar's Sceptre was not.
The story was redrawn and colourised in 1947. For this edition, Hergé was assisted by Edgar Pierre Jacobs, a highly-regarded artist in his own right. Jacobs is credited with much of the Balkan feel of the new edition.
In terms of the plot and appearance of the characters, the two editions are generally similar. The principal aesthetic difference, aside from the colour, is that the backgrounds in the 1938-39 edition were generally blank, whereas in 1947 the streets of the towns, the countryside and the interior of the flats and palaces are more detailed.
Other changes affected the appearance of the Syldavian court. In the 1938 version, the Royal Guards are dressed like British Beefeaters; the 1947 version has them dressed in a more Balkan-like uniform. In 1939, Tintin is knighted while dressed in his raincoat, and a tear comes to his eye when he receives his medal in a ceremony which, aside from the Queen, is attended only by men; in 1947, he wears a suit, shows embarrassment but no tears, there are ladies attending, and there are also caricatures of Hergé and Jacobs in uniform, along with a number of colleagues and relatives .
All the aircraft featured in the book are carefully drawn from real contemporary designs . In the 1939 version, the plane Tintin uses to escape from Borduria, seems to resemble a Heinkel He 118. However, in the 1947 version, the Heinkels are replaced by the more famous Messerschmitt Bf 109s.
Although the twin detectives had first appeared in Cigars of the Pharaoh in 1934 and had featured in the three adventures that followed, they were not given actual names until the 1938-9 King Ottokar's Sceptre when Tintin introduces them by name to Alembick at the airport.
Two recurring Tintin characters are introduced in King Ottokar's Sceptre: Bianca Castafiore, and Colonel Boris, who was to re-appear under the name of Jorgen in Destination Moon and its sequel Explorers on the Moon.
Like many of the fictional languages in the Tintin books, the Syldavian language is based on the slang of the Marolliens, the people of the working class quarter of Brussels, with the addition of some s and z sounds to make it sound more Slavic. For example, the Syldavian motto, "Eih bennek, eih blavek", means "If you gather thistles, expect prickles" according to the book, but the 'Syldavian' words in fact resemble Marollien dialect for "Here I am, here I stay."
The 1990s Adventures of Tintin animated series changed the story slightly to make the Alembick twin who smokes the bad one of the two.
In addition, the brochure on Syldavia read by Tintin states that Syldavia, along with the rest of the Balkans, was invaded by the Turks in the 10th century. As the Turks were not to invade the Balkans until the second half of the 14th century, this seems improbable.