Tintin begins his greatest adventure when he and Captain Haddock are rather cryptically summoned to join Professor Calculus in Klow. It turns out that the professor has joined a consortium in order to build a rocket that will land a person on the moon (this was in 1953, well before Neil Armstrong). Unfortunately, the project has attracted some unwanted attention from those who will resort to sabotage and skullduggery to steal the technology. Is the project successful? Well, it's probably not that great of a spoiler to reveal that the story is continued in Explorers on the Moon.