Ghost Whisperer Episode 1.03 Ghost, Interrupted

A young girl, Natalie, is placed in a psychiatric facility for her strange behavior following her identical twin sister Zoe's death. While on a field trip in town, Natalie runs away from her group and tries to hide in Melinda's shop. Melinda quickly realizes that Natalie's 'abnormal' behavior is due to her sister haunting her. Zoe is earthbound because of a devastating secret she took with her to the grave: she slept with Natalie's boyfriend while intoxicated and while Natalie was asleep. Natalie is shattered when she finds out, and confronts her boyfriend. She hijacked her boyfriend's car, and then drove to the lake where her sister drowned. Zoe assumes Natalie is going to drown in the lake, and appears before Melinda, who is having dinner her friends Will and Andrea, who she's trying to matchmake. Melinda and her husband Jim drive to the lake, calling the twins' father along the way, and find Natalie already swimming away from shore. As Jim is about to dive into the water, Zoe tells him through Melinda to stop. As they watch, Natalie fulfills the twins' childhood ambition of reaching the buoys in the middle of the lake and tapping it three times. Neither twin has accomplished this before. The twins' father arrives, just as Natalie reaches the shore and they share a heartfelt goodbye with Zoe. The twins forgive each other, and their father tells Zoe that he has never compared her to Natalie, that he sees her for who she is, and not just Natalie's twin. This brings closure for all three of them, and Zoe fades away into a light only she can see.