An idol that originally belonged to a Native American nation in South America is stolen from the Museum of Ethnography in Brussels. The following day it is back in the museum along with a note apologizing for the inconvenience caused saying that the reason for the theft had been a bet. Tintin who is among the reporters looking into the story realizes that the replacement is a fake the distinction being an ear broken on the original but intact on the replacement.He peruses a book from his own library with an image of the idol drawn by an explorer: it confirms that one of the ears is damaged while the one back in the museum is not. Tintin then reads that a wood carver called Balthazar has died apparantly fromm a gas leak. However his parrot has survived despite the leak. Tintin realises he was murdered and the gas turned on later to make it look like an accident. Suspecting that Balthazar made a duplicate of the idol and was murdered Tintin tries to obtain the man''s parrot in order to get a clue to the killer''s identity. But he soon discovers that a pair of South Americans Alonso Perez and Ramon Bada are also on the trail of the idol following the same clues and employing more ruthless methods. They even make attempts on Tintin''s life.