So what exactly is a Ragnarok when it's at home? We'll attempt to answer this and several other burning questions about the upcoming third Thor movie.
What's this Ragnarok then, eh?
It's curtains, basically. In Old Norse mythology, this is the big one. It translates more-or-less literally as "twilight of the gods". A great apocalyptic showdown between all our favourite gods and the giants of frost and fire leads to the total destruction of the planet and the deaths of all and sundry as the world is submerged in water.
The upside? Well, unlike Christian End Times there's something of a remarkable comeback. The planet pops out of the water again, all green and fertile, the gods reunite, and a pair of surviving humans set about the arduous business of repopulation. It's like pressing a bloody great 'reset' button, basically.
So how does that relate to the movie?
Well, Chris Hemsworth's Thor has to stop all this happening by returning to Asgard to prevent Cate Blanchett's villainous Hela from triggering Ragnarok. But before he can do that, he needs to defeat former chum and fellow Avenger Hulk (Mark Ruffalo) in a gargantuan gladiatorial smackdown.
What do we know about Hela?
She's quite the baddie. The Marvel character is based on the deity Hel, from Norse mythology, who rules an underworld also named Hel, where many of the dead hang out.
Although they share an etymology, the Norse Hel is quite different from the Christian Hell. It isn't a place where you go to suffer in eternal torment for doing bad stuff, but simply one of many afterlife realms. According to some sources, Hel was rather pleasant.
Anyway, that's enough Old Norse mythology. As played by Cate Branchett in the movie, Hela is nothing less than the goddess of death. It doesn't help that she's very angry indeed. Well, wouldn't you be if you'd been imprisoned for millennia? Weapons? She gottem! Blanchett has revealed that her character is able to manifest them from various parts of her body as well as that strikingly cool horny headdress.
Where's Loki in all of this?
All eyes are on Hella as the Thor series' first female villain, so where does that leave the trickster Loki? Has he been usurped? Hardly.
At the end of Thor: The Dark World, you'll recall, he disguised himself as Odin to nab the throne of Asgard. But if there's one thing Loki isn't cut out to be, it's a ruler. So naturally things seem to have gone rather pear-shaped in Thor's absence.
Loki seems to have formed some kind of alliance with arch-manipulator Grandmaster (Jeff Goldblum), who rules the planet Sakaar with an iron fist. And while the identity of whoever released Hella has not been revealed, Loki must figure right at the top of the list of suspects.
What's the really cool, driving rock song that plays throughout the trailer?
That's Immigrant Song by Led Zeppelin from their Led Zeppelin III album.
It's an apt and playful choice given that Robert Plant's lyrics refer to "a land of ice and snow" and "the hammer of the gods", as well as making reference to Valhalla. The song is about a band of Vikings heading west in search of new lands to conquer.
It was also used in the Jack Black comedy, School of Rock.
Thor: Ragnarok lands at Cineworld on 27 October.