Synopsis
Tintin finds a lost briefcase and returns it to the owner, Professor Hector Alembick, who is a sigillographer, an expert on seals (as in the sort used to make state documents official). He shows Tintin his collection of seals, including one which belonged to the Syldavian King Ottokar IV. Tintin then discovers that he and Alembick are under surveillance by some strange men. Tintin's flat is even bombed in an attempt to kill him. Suspecting a Syldavian connection, Tintin offers to accompany Alembick to Syldavia via Frankfurt and Prague for research.
On the plane Tintin begins to suspect his companion. The Alembick travelling with him does not smoke and doesn't seem to need the spectacles he wears – to the point that he can make out a pretty pattern made by the sheep in a field that the plane passed over – while the Alembick he first met did smoke and had poor eyesight. During a layover, Tintin fakes a fall and grabs Alembick's beard, thinking it is false and Alembick is an imposter. However, the beard proves to be real and Tintin decides to let the matter drop, assuming that Alembick simply gave up smoking and is better at long distances than close-up- 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, a tradition established after a past king used the sceptre to defeat a would-be assassin. 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 – the thief throwing the sceptre through the iron bars over the window – proves to be inaccurate. 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 'shoot' the sceptre out of the castle through the window bars 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 wrestles 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 a takeover 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 invasion 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 King Muskar XII 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 King Muskar XII the papers he took from the man who stole the sceptre. They prove that the plot was masterminded by Müsstler, leader of the Zyldav Zentral Revolutzionär Komitzät, a political organisation. 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.
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 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.
Read more about this topic: King Ottokar's Sceptre