Bound for an Astronautical Congress in Australia. Tintin, Snowy, Captain Haddock and Professor Calculus accept a lift in the private jet of Laszlo Carreidas, the millionaire who never laughs. The plane is hi-jacked, and the millionaire and his guests are landed on a Pacific island. Their old enemy Rastapopoulos awaits them. Using a truth drug on Carreidas, he hopes to extract the number of the millionaire's secret Swiss bank account, but, thanks to Tintin, his plans go strangely awry.