The setting, as I’m sure many are familiar with, is placed 10 years after the events of Revenge of the Sith whilst Obi-Wan is in hiding from the Empire and watching over Luke Skywalker.
Hope is brought up a lot in the trailer, so the plot will likely focus on a test of faith for Obi-Wan. How the writers test that faith we can only guess at but given Obi-Wan’s despondent disposition in the trailer and the use of both “Duel of Fates” and “Battle of the Heroes” means that test will likely come in the form of Darth Vader himself or failing that, Vader’s son Luke. Episode Four is called A New Hope after all, so maybe this miniseries will bridge the gap and explain in detail how Kenobi came to believe in this boy as, wait for it, a new hope in the galaxy.
The main antagonists will be the Inquisitors, a group of force-sensitive people and former Jedi turned to the Dark Side to hunt any remaining Jedi that survived Order 66. Obi-Wan will likely be drawn to their cruelty and his need to stop it, at which point the Inquisitors will try to hunt and kill him. When they fail, Darth Vader himself will face Obi-Wan.
One theory posited by Screen Rant, suggest that Reva will be the main antagonist. This is because Inquisitors aren’t supposed to have names, hence Fifth Brother, Third Sister etc. in order to strip their identities and build them back up again as Jedi hunting machines. The fact that her name is Reva suggests that she is a special case who has distinguished herself so greatly that her name has been returned to her. She is described as “ruthlessly ambitious” and maybe she wishes to become the Grand Inquisitor, hence her desire to catch Obi-Wan.