A new Fire Emblem Engage story trailer has been revealed, setting up the narrative for the game ahead of its January release. You're on the hunt for twelve rings, which give you the power to summon Emblems to help you and may also assist in recovering your memory.
Fire Emblem Engage was originally announced back in September as part of a Nintendo Direct presentation. During that presentation, we learned that rumors surrounding the main character's design and the ability to summon past Fire Emblem characters were largely correct, and that the game will arrive in January.
Now, Nintendo has released a brand new trailer showcasing the world of Elyos. At the outset, protagonist Alear watches someone dear to him die. She implores him to find "all twelve rings" and recover his "scattered memories". Searching for those twelve rings seems like it'll take up the bulk of Fire Emblem Engage's plot, during which Alear will meet and befriend (or make enemies of) various characters from Elyos' four kingdoms.
Fire Emblem series mainstay Marth figures heavily into the plot of Fire Emblem Engage; he seems to be the first Emblem that Alear can summon, and he also appears to know Alear personally. Marth says Alear summoned him because our red-and-blue-haired protagonist "remembered [Marth]".
As the trailer continues, we see Alear forging alliances with citizens of different kingdoms, including Brodea (or perhaps Brodia), the "Kingdom of Might". There's also a winter kingdom that takes the role of antagonist in Alear's story, and looking at the characters who hail from that kingdom, it's pretty easy to see why.
During the concluding moments of the new Fire Emblem Engage trailer, one of the antagonists reveals that Alear isn't the only one who can command the power of the rings. The bad guys turn Marth to their side, and Alear is forced to watch as Marth unwillingly becomes his opponents' pawn. It looks like you're going to have to fight against the Emblems you summon, too, although it's not clear whether this just affects Marth or all the other Emblems you can call on.

We'll likely learn more about Fire Emblem Engage, its setting, and its gameplay as we draw nearer to the game's January 20th release date. In the meantime, you can head over to the Nintendo eShop if you want to preorder Fire Emblem Engage.