Ghost of Relativity.

Keung Yung has had a crush on her co-worker Michael Chiu Wai Kan for over ten years, but she is too afraid to confess her feelings. One night while talking on the phone with her other co-worker Shun Suk Mui, Yung is electrocuted to death because of her bootlegged phone. Regretful of not being able to fulfill her romantic wishes in life, she uses Suk Mui, who is the only person that can see her due to their final phone conversation, to pursue Michael.