Tintin and his dog Snowy are on a cruise ship in the Mediterranean Sea when they meet Dr Sarcophagus, an Egyptologist who owns a papyrus that he believes will lead him to the undiscovered tomb of the Pharaoh Kih-Oskh (a pun on kiosk, a stand for the sale of petty merchandises such as newspapers, magazines, cigarettes, beverages and/or street foods). He invites Tintin to accompany him. Tintin also has an unpleasant encounter with Roberto Rastapopoulos, a wealthy businessman.

Later on the cruise, Tintin first meets Thomson and Thompson, who accuse him of smuggling opium and cocaine they have found in his cabin. Locked in the hold of the ship, Tintin craftily escapes and meets Sarcophagus in Port Said, Egypt.

Tintin and Sarcophagus set off and discover the tomb of Kih-Oskh. On a nearby sand dune, Tintin finds a cigar bearing the symbol of Kih-Oskh: a circle with a wavy line through it and two dots on it, rather like a yin-yang symbol. But when he returns to the tomb, Sarcophagus has disappeared.