The trailer doesn't reveal much about the film's plot — it's just a teaser, after all. But here's a scene-by-scene analysis of what we're seeing and hearing, or maybe seeing and hearing.
We open with Rey (Daisy Ridley) in distress, wearing the same garb as when we left her in The Force Awakens. It's pretty clearly the same planet where she met Luke Skywalker (Mark Hamill), too. It doesn't read like she was physically attacked, however — it looks more like she's coming out of some kind of Jedi-style I-just-saw-the-future trance, similar to after she touched Luke's lightsaber in TFA.
Yup, totally Luke's planet.
"Breathe. Breathe," says a voice that almost certainly belongs to Skywalker. Meanwhile, Rey is looking like she's about to go full Charlton-Heston-as-Moses on that seaside. It seems an awful lot like Luke is training Rey in the ways of the force the way Yoda trained him on Dagobah.
A hand, probably Rey's, is touching the ground, and some small pebbles are floating around her. Yeah, this is totally a Jedi training montage. Cue the Rocky music.
"Now, reach out," says Luke. "What do you see?" Hard cut to the back of General Leia Organa's head. "Light," answers Rey. You can make out Leia's classic line from A New Hope in the background "Help me, Obi-Wan Kenobi, you're my only hope." (Carrie Fisher passed away in December, but she had already filmed her scenes for The Last Jedi.)
Cut to a mask, which looks like Darth Vader's, smoldering on the ground. There's the unmistakable sound of Vader's breathing apparatus, too. "Darkness," says Rey. (My colleague John Patrick Pullen argues that it's Ren's mask, not Vader's, which I could totally see.)
If you listen very closely, you'll also hear what sounds a little like Obi-Wan Kenobi explaining Vader's fate to a young Luke in The Return of the Jedi: "Your father was seduced by the dark side of the Force."
We last saw Vader's mask in slightly melted but overall decent shape in the possession of one Kylo Ren (Adam Driver). Does Ren destroy his grandfather's mask in another fit of rage?
Now a shot of a hand gently gliding over a very old book with a version of the Jedi symbol. (Pullen also says this might be the Journal of the Whills, a Jedi religious tome made canon in the Force Awakens novelization.)
"The balance," says Rey. And again, another familiar voice in the background: Jedi Master Yoda, but what he's saying is hard to make out. (Pullen says it's a version of a line of his from Return: "Luke, when gone am I...the last of the Jedi will you be." That jives with this movie's title.)
It could be that Rey goes on a quest to learn more about the Jedi and the Force, or perhaps this is on Luke's hideaway planet, which may be the site of the first Jedi temple.
Next, a pretty epic shot of Rey and what looks like Luke doing some lightsaber training on Skywalker's planet again. "It's so much bigger," says Luke. And that's when this trailer party really gets started.
Here we've got some unknown and pretty run-down looking ships (or speeders, even) headed full-speed into a phalanx of Imperial/First Order-style walkers. No idea who these dudes are.
Hey, Finn's (John Boyega) back! And he's in some kind of stasis tube, perhaps still recovering from the injuries he sustained at the end of The Force Awakens.
Poe Dameron (Oscar Isaac) and droid pal BB-8 are looking very determined to get to their X-Wing...
But then it goes boom. Hate it when that happens. (Nerd sidebar: A-Wings are still around! Those are great wings!)
Obligatory "The Millennium Falcon is being chased by some TIE Fighters" shot.
We're definitely getting another lightsaber fight, y'all. I love the way Ren's lightsaber is reflected in his eyes in this shot — gives him some serious Anakin-on-Mustafar vibes.
R2-D2 and a robed figure arrive at some kind of burning structure or battlefield. The robed figure plops to the ground, seemingly defeated. Is that Luke or Rey? Who torched the town? If that's Luke, this whole mess is gonna trigger some big-time Uncle Owen feels.
Captain Phasma (Gwendoline Christie) is back, shiny and chrome. I hope she gets more screen time.
Space dogfight! My only takeaway here is that it's interesting to see so many similarly-designed larger ships in a presumably Rebel/Resistance fleet, which are usually more of a hodgepodge. Maybe this is a more unified military power of some kind?
And here's the big finale, via Skywalker himself: "It's time for the Jedi to end."
That line is the only nugget in the teaser that gives us something to really chew on. Why does Luke, who once wanted nothing more than to become a Jedi, now want them gone?
Perhaps it's about balance in the Force. If Luke and Rey can kill (or otherwise neutralize) Ren and Supreme Leader Snoke (the big ghost-like dude in The Force Awakens, who is presumably calling the shots over on the dark side), then maybe Luke thinks they should then sacrifice themselves, leaving the galaxy for the non-Jedi and non-Sith to handle.
Or maybe it turns out that Luke trained Ren to be a Jedi before he turned to the dark side and killed his buddy Han, leaving Luke emotionally scarred to the point where he's unwilling to train any more. He's definitely training Rey in this trailer, but maybe that takes some convincing on her part, and this scene comes early in the story and is far less ominous than it seems.
There is, of course, a third option: Luke's been isolated for so long that he's simply gone nuts and maybe even a little evil. That'd be fun! Either way, we'll have to wait until December to find out.