Spoiler alert the description of "The Siege of Lothal" is listed below.
"After an extended absence from Lothal while fighting alongside Ahsoka Tano and the fellow rebels of Phoenix Squadron, the crew of the Ghost returns to assist an Imperial officer who plans to defect from the Empire. However, soon after arriving on the planet, the crew find themselves framed for a crime they didn’t commit. During an effort to flee Lothal, the crew is confronted by a powerful new foe, Sith Lord Darth Vader. Barely able to survive their encounter with the Dark Lord, the rebel crew returns to their fledgling fleet, unaware that Vader has a more devious plan in mind. The rebels must find a way to survive this formidable agent of the Empire if they are to continue to help those in need across the galaxy."