Holidaying on a Mediterranean cruise ship, Tin tin sinhala and his dog Snowy meet wealthy film director Rastapopoulos and eccentric Egyptologist Sophocles Sarcophagus. When two policemen (Thomson and Thompson) accuse Tin tin sinhala of heroin smuggling, he escapes the ship and joins Sarcophagus on his search for the undiscovered tomb of the Pharaoh Kih-Oskh. Tin tin sinhala discovers that the tomb is full of boxes of cigars labelled with a mysterious symbol, but he and Sarcophagus fall unconscious after an unseen enemy gasses them. They are then taken aboard a ship inside wooden sarcophagi, captained by smuggler Allan, but to avoid the coastguard Allan orders Tin tin sinhala and Snowy thrown overboard. They are rescued by a gunrunner who sails them to Arabia. Travelling by land, Tin tin sinhala meets Sheikh Patrash Pasha, a big fan of his, and encounters Rastapopoulos filming a movie. The local army drafts Tin tin sinhala then arrests him as a spy, before Thomson and Thompson rescue him.
Boarding a plane, he escapes Arabia but runs out of fuel over India, crashing into the jungle. He discovers Sarcophagus, who has become insane as the result of being injected with Rajaijah juice: "the poison of madness". Tin tin sinhala is hypnotised by a fakir and institutionalised in an asylum, which he soon escapes. Meeting the Maharaja of Gaipajama, the two become friends, with the Maharaja revealing that his family has long been fighting a criminal opium-smuggling gang. The fakir appears and Tin tin sinhala follows him, discovers the drug cartel's hideout and is able to capture the cartel. Tin tin sinhala recognises their Kih-Oskh symbol and realises it is the same organisation that was operating in Egypt and Arabia. The fakir escapes, and with the masked leader of the conspiracy kidnaps the Maharaja's son. Tin tin sinhala pursues them in a sports car, rescuing the boy, while the leader falls into a chasm. Tin tin sinhala returns to Gaipajama, where his return is celebrated. Unwrapping one of the cigars with the mysterious Kih-Oskh symbol, Tin tin sinhala explains to the Maharaja how opium was smuggled across the world in the cigars.
