Actually no, more like, Vader comes into the story , most likely near the finale. He is on a quest to kill a suspected Jedi, or find a holocron or something.....and at the same time , Obi is going for the same goal or just trying to prevent Vader from succeeding. These would be tales of smaller goals. Basically the would show Obi doing everything in his power to slow the ascent of the Empire, delaying whatever he could without compromising his main goal. The struggle would be him trying to stop the Emperors plans as much as possible while at the same time, keeping Luke and Leia safe.