Here's the official plot synopsis for Solo:
Board the Millennium Falcon and journey to a galaxy far, far away in "Solo: A Star Wars Story," an all-new adventure with the most beloved scoundrel in the galaxy. Through a series of daring escapades deep within a dark and dangerous criminal underworld, Han Solo meets his mighty future copilot Chewbacca and encounters the notorious gambler Lando Calrissian, in a journey that will set the course of one of the Star Wars saga's most unlikely heroes.
Chewbacca only shows up at the end of the trailer — it's likely we'll see more of him in the full length trailer, debuting tomorrow on ABC's Good Morning America — making it hard to guess how the iconic smugglers and best friends will first come to meet.
In the original Extended Universe canon, which was erased by Disney following their 2012 purchase of Lucasfilm, the Wookiee warrior was already nearly 200 years old before his adventures in the Clone Wars (seen in canonical Star Wars: Episode III — Revenge of the Sith).
There Chewbacca fought alongside Jedi Master Yoda on his home planet of Kashyyyk, eventually helping the pint-sized Jedi escape an assassination attempt on his life made by a pair of Clone Troopers.
As the Galactic Empire was birthed out of the fall of the Republic, many Wookiees found themselves enslaved and put to work on planets like Kessel, home to spice mines and the Empire's expansive harvesting operation.
Chewbacca was enslaved by the reptilian Trandoshans and forced to cut trees to feed Imperial armies, where he met a young Han Solo.
Solo, who was accepted into the Imperial Academy on Coruscant under a fake identity, eventually served in the Imperial Starfleet, earning top piloting marks.
It was during this time Solo came across a wounded Chewbacca and a slaving craft full of Wookiee children, causing Solo to disobey the orders of his commanding officer, Commander Nyklas.
He attacked the commanding officer, make a daring escape with Chewbacca — actions that saw Solo dishonorably discharged. His military career ended, the young Corellian returned to his life as a smuggler alongside new ally Chewbacca, who swore an unbreakable life debt to his rescuer.
Solo seems to borrow inspiration from the classic Expanded Universe stories: the TV spot sees Han enlisting in the Empire military with aims of becoming a pilot, and Han and Chewie are later spotted together overlooking the ocean — which very well could be the shores of Kashyyyk.
Directed by Ron Howard and starring Alden Ehrenreich, Donald Glover, Emilia Clarke, Joonas Suotamo, Thandie Newton, Paul Bettany, and Woody Harrelson, Solo: A Star Wars Story opens May 25.