In 1932, Tintin, a reporter for Le Petit Vingti?me, goes with his dog Snowy on an assignment to Chicago, Illinois, to fight against the city's organised crime syndicate. Soon after arriving there, Tintin and Snowy are kidnapped by gangsters and brought before mobster boss Al Capone, whose criminal enterprises in the Congo were previously thwarted by Tintin. With Snowy's help, Tintin subdues his captors, but as he goes to inform the police, they reject his claims, and the gangsters escape while Tintin is away. After surviving attempts on his life, Tintin meets Capone's rival Bobby Smiles, who heads the Gangsters' Syndicate of Chicago. Tintin is unpersuaded by Smiles' attempt to hire him, and after Tintin orchestrates the arrest of his gang, Smiles escapes and heads west. Tintin pursues Smiles to the Midwestern town of Redskin City. Here, Smiles convinces a tribe of Blackfeet Native Americans that Tintin is their enemy, and when Tintin arrives, he is captured and threatened with execution. After escaping, Tintin discovers a source of underground petroleum. The U.S. army then forces the Natives off their land, and oil companies build a city on the site within 24 hours. Tintin evades a lynch mob and a wildfire before coming across train tracks which he decides to follow in order to get back to civilization and continue on Smiles' trail. However, he is ambushed by the gangster and one of his associates, who ties him down to the tracks to be killed by a train scheduled to come through. However, the train happens to stop right before running him over and he is safely rescued, allowing him to continue on his search and find Smiles' remote hideaway cabin. After a brief altercation, he finally captures the gangster. Returning to Chicago with his prisoner, Tintin is praised as a hero, but gangsters kidnap Snowy and send Tintin a ransom note. Tracing the kidnappers to a local mansion, Tintin hides in a suit of armor and frees Snowy from the dungeon. The following day, Tintin is invited to a cannery, but it is a trap set by gangsters, who trick him into falling into the meat-grinding machine. Tintin is saved when the machine workers go on strike and then apprehend the mobsters. In thanks, he is invited to a banquet in his honor, where he is kidnapped. His captors tie him to a dumbbell and throw him into Lake Michigan to drown, but Tintin survives by floating to the surface, with his dumbbell having been accidentally replaced with a fake. Gangsters posing as police capture him, but he once again overwhelms them and hands them over to the authorities. Finally, Tintin's success against the gangsters is celebrated by a ticker-tape parade, following which he returns to Europe.