Taking place after the events of Episode VII Rey is training with Luke to advance her skills in the force. through out the film he has flashbacks to his Jedi order being wiped out as Snoke seduced Kylo and a few of the other students to the dark side and tasked them with killing everyone. Luke and a few others survived, including a young Rey who was subsequently left on Jakku by Luke, while her mother is presumed dead. With Mara and Valvark they run into Luke, Rey and chewbaca and Luke and Tharicia recognize each other to which Rey realizes She's her mother and the three plan an attack.