The ghosts of Split River High School are spiraling over a surprise - and heartbreaking - exit in a first look at the School Spirits season 3 finale. In Us Weekly's exclusive sneak peek of the Wednesday, March 4, episode, the teen spirits are left facing the fallout after Wally (Milo Manheim) secretly left the group behind in hopes of finding girlfriend Maddie's (Peyton List) best friend, Simon (Kristian Ventura), amid his mysterious disappearance.