[[quoteright:300:http://static.tvtropes.org/pmwiki/pub/images/album-tintin-seven-crystal-balls_4866.jpg]]Tintin goes to visit Captain Haddock and Professor Calculus at their new home in Marlinspike Hall. On the train, he reads about a team of seven explorers led by Professor Sanders-Hardiman (Sanders-Hardmuth in the original French) returning home after a two year expedition in the Andes where they discovered the tomb of the ancient Incan ruler Rascar Capac, with the latter's mummy in tow. A strange man compares them to the Egyptologists who unearthed Tutankhamen's tomb and claims the same fate will befall them. Later on, Tintin attends a music hall with Haddock and is surprised to see General Alcazar, who since ''[[Recap/TintinTheBrokenEar The Broken Ear]]'' was deposed and now is performing as a knife thrower. Another act by a psychic also mentions the expedition and warns its members are in grave danger.

Concurrent with these events, each member of the Sanders-Hardiman expedition starts falling into a mysterious coma, one by one. Thompson and Thomson are investigating and reveal that the only clue present at each scene are fragments of crystal spheres, which apparently contained some sort of mysterious gas that caused the comas. Despite the efforts of Tintin, Haddock, and the Thompsons, they are unable to stop the attacks and finally decide to personally guard the last explorer, Professor Tarragon (Bergamotte in French), an old friend of Professor Calculus, who accompanies them to the former's house. After Rascar Capac's mummy disappears from the house in a mysterious bolt of ball lightning, Tarragon claims that this is the culmination of a prophecy: Rascar Capac has "returned to his element" and will go after Tarragon personally. Despite the escort, Tarragon succumbs to the coma as well, becoming the last of the seven. To make matters worse, Professor Calculus is kidnapped after finding the mummy's bracelet.

Tintin and Haddock chase the kidnapper and manage to track him to the ''Pachacamac'', a ship bound for Peru. Tintin also discovers that Alcazar's assistant Chiquito, one of the last descendants of the Incas is also involved. Tintin and Haddock depart for Peru to rescue Calculus, closing part 1 of the two part story that concludes in ''[[Recap/TintinPrisonersOfTheSun Prisoners of the Sun]]''.

''The Seven Crystal Balls'' is the last story that Hergé produced as a daily comic strip for the "Stolen ''Soir''" during the German occupation of Belgium. It was at first left unfinished after the liberation of Brussels restored ''Le Soir'' to its rightful owners and staff and Hergé was briefly jailed as a collaborator. Starting in 1946 was serialized once more and completed (with an extensive rewrite of the ending as far as it had been done in 1944) in the new comic magazine ''Tintin'' and then produced in album form. This enabled Hergé to take out old panels, add new ones, polish up the art and text and to change the layout without being bound by the constraints of the format used in the newspaper. This is most noticeable in the classic backstage slapstick sequence with Haddock in the music hall. A reprint of the 1943-1944 black-and-white strips with extensive comments and background information by Philippe Goddin was produced by Editions Moulinsart in 2012 under the title ''Les mystères des 7 Boules de cristal''.

* AndIMustScream: The seven explorers themselves, especially Professor Tarragon.
* CallBack: See below.
* ContinuityLockout: An extremely minor example, but when our heroes are contacting the explorers to warn them of the curse, Professor Cantonneau greets Tintin on the telephone as an old acquaintance ("My dear Tintin"). This is because Cantonneau was also one of the scientists aboard the Aurora in ''[[Recap/TintinTheShootingStar The Shooting Star]]''. It's a nice little grace note, but perhaps too subtle, as there isn't a word of explanation as to how the professor already knows Tintin. However, when the story first appeared it was only about three years since ''The Shooting Star'' was serialized and less than two since it was republished as a colour album, and besides the sequence in ''Crystal Balls'' is so short (six panels) that it does not merit the extra space needed to explain that Cantonneau has met Tintin and Haddock before.
* {{Curse}}: The explorers and archaeologists all fall victim to a curse due to desecrating a tomb. Subverted in that it requires human agents to make the curse come true for them.
* DangerousWindows: Two of the members of the Sanders-Hardiman expedition fall victim to crystal balls hurled through their windows. Professor Cantonneau is attacked this way just as Tintin tries to warn him not to go near the window. Dr. Midge is then placed under police guard, but the police in question are Thompson and Thomson, and they try to guard everything but the window. With predictable results. [[CatchPhrase To be precise]], the two of them freak out over a brown paper package, fearing it contains a bomb or pathogen, and ''both'' go into another room to examine it, leaving the professor completely unguarded. [[RedHerring The package has a butterfly specimen in it.]]
* FaintingSeer: Mrs. Yamilah, a stage fortune teller, tries to look into the fate of a woman married to one of the explorers. She gets a glimpse into the fate of the husband and seems physically affected.
* {{Fireballs}}: A huge fireball of lightning crashes into the protagonists' household. What some readers may be amazed to know is that this phenomenon actually has some basis in reality. Ball lightning is one the least understood meteorological phenomena known to man. Essentially a ball of light that occurs during a thunder and or lightning storm, these little (or huge) buggers have been known about since antiquity. Nobody knows exactly what the stuff is though, other than a ball of light with electric properties. Its reported characteristics vary wildly, some times it can pass though people without out harming them or times they discharge massive amounts of electricity, even up to a normal lightning strike.
** ScienceMarchesOn: Up until the 1960s scientists were skeptical of the very existence of ball lightning, putting them on the level of {{Flying Saucer}}s and other hocus pocus. Hence their mystical properties as shown on the book cover.
* HighClassGlass: In the previous adventure, ''[[Recap/TintinRedRackhamsTreasure Red Rackham's Treasure]]'', Captain Haddock had acquired a treasure through inheritance. His newfound wealth is indicated in this album by his residence in a mansion and by his new habit of wearing a monocle. Not being accustomed to them, he loses a lot of them.
* KnifeThrowingAct: General Alcazar, exiled in this book, has his own stage act. After creating a full KnifeOutline around his Indian partner, he asks an audience member to blindfold him. His blind throw hits right in the center of the tiny disc-shaped target held over the Chiquito's chest.
* AMythologyIsTrue: In-story example. The curse of Rascar Capac is scoffed at by the rational characters. Until it turns true to the letter.
* NightmareSequence: Tintin and his companions all have the same nightmare: that they are visited by the Inca mummy Rascar Capac who enters their bedroom by night and then throws a crystal ball on the floor.
* NoCommunitiesWereHarmed: The ending of the story is partly set in the French ports of Saint-Nazaire and La Rochelle, which Titin and Haddock reach from Belgium by car. As the English translation relocates the home setting to England (Marlinspike in Marlinshire), it renames the ports Westermouth and Bridgeport.
* RealLifeWritesThePlot:
** Much like ''Recap/TintinCigarsOfThePharaoh'' the plot was inspired by the so-called ''curse of the mummy'' surrounding the opening of pharao UsefulNotes/{{Tutankhamun}}'s tomb in 1922, only with the action brought to Peruvian mummies instead of Egyptian ones.
** Professor Tarragon's house really exists in Brussels. During the Nazi occupation of Belgium, when this story was made, Creator/{{Herge}} and his assistant Bob De Moor went to the house to draw sketches of it. They had just finished and were about to leave when they saw a car full of SS soldiers drive to it in the distance. Apparently it was used as one of their headquarters! When Hergé told this anecdote to a journalist after the war he added: "If they had turned up a little earlier they would've probably have spotted our suspicious activity and forced us to explain what we were doing there."
* ReallyRoyaltyReveal: When Tintin meets Alcazar at the port, he asks him if his now missing partner was a real Indian. Alcazar replies that Chiquito not only was a full-blooded Quechua, but an actual descendant of the Inca rulers called Rupac Inca Huaco.
* RuleOfSeven: Seven cursed explorers, seven crystal balls hurled at them and and placing them in comas.