Tintin au pays de l'or noir (1950)

Car engines are spontaneously exploding all over the country. The reason is narrowed down to the petrol used in the cars which is tampered in some way to cause an explosion. As a result most form of transport from cars to airlines are cutting down on fuel usage, thus affecting the economy.

Furthermore political tensions are heightening, leading the world to the brink of war, and Captain Haddock is mobilised in anticipation of an outbreak of hostilities. Following different leads, Tintin and Thomson and Thompson set off for Khemed on board a petrol tanker. Upon arrival, the three are framed and arrested by the authorities under various charges. The Thompsons are cleared and released, but Tintin is kidnapped by Arab insurgents.

In the course of his adventures, Tintin re-encounters an old enemy, Dr. J.W. Müller , whom he sees sabotaging an oil pipeline. He reunites with the Thompsons and eventually arrives in Wadesdah, the capital of Khemed, where he comes across his old friend, the Portuguese merchant Senhor Oliveira da Figueira. When the local Emir Ben Kalish Ezab's young son, Prince Abdullah, is kidnapped, Tintin suspects that Müller is responsible. He pursues Müller in hopes of rescuing the prince and gets into his study. After an incident involving sneezing powder he is able to knock out Muller. He ties him up, gags him, and hides him behind the sofa. He then rescues the Prince and later captures Muller. Captain Haddock comes along near the end of the book, but it is never explained how this happens. In the process he discovers the doctor to be the agent of a foreign power responsible for the tampering of the fuel supplies, having invented a type of chemical in tablet form that increases the explosive power of oil by a significant amount. The Thomson twins find the tablets and swallow them, thinking them to be aspirin, causing them to belch continuously, and grow long hair and beards that change colour.

After analysing the tablets, Professor Calculus comes up with remedies for the Thompsons and a means of countering the affected oil supplies, though, while carrying out his tests, he half-destroys Captain Haddock's Marlinspike Hall, earning the Captain's fury.