May Suen Suk-Mui (Kristal Tin) is an absent-minded, dim-witted, unambitious thirty-something year old, who gets lucky during her job interview as a receptionist at GSZ Architects Limited. The human resources manager Ma Mei-ching, had unconsidered her for the position after seeing she was late to the interview and had unimpressive work experience. However office manager Gin Keung Yung (Nancy Wu) comes to May's defense when the human resource manager loudly mocks May in front of others. Gin points out the flaws of the other applicants and deems them unpresentable for the receptionist job. With Gin's comments about the other applicants, May is hired on the spot against the human resource manager's wishes.
GSZ Architects Limited's office manager Gin is feared and respected by all at the office. She has been in love with architect Michael Mai Hoi-long (Moses Chan) for many years, and she drops hints about her feelings for him hoping he will know how she feels, but Michael is too involved in his work to notice Gin and only thinks of her as an extra supportive co-worker. Gin has patiently waited and supported Michael for many years hoping when he receives the recognition he desperately seeks for his designs, he will put his work behind him and finally notice her.
May gets fired on her first day at work when she is blamed for Michael losing a design award. However, due to her stupidity earlier in the day, while comparing her counterfeit designer handbag to Gin's almost identical authentic designer handbag, she confusedly switches their handbags and is forced to return to the office later that night to return Gin's handbag. While talking on the phone with Gin to obtain the office tower's entry pin number, Gin gets electrocuted to death on May's dangerously high voltage counterfeit cellphone.
One year later May is chased by debt collectors for a loan she got for her con-artist boyfriend Wong Tai-lung. When the police calls her to collect her handbag that was previously in Gin's possession, she desperately uses the counterfeit cellphone that killed Gin to try to call authorities when the debt collectors trap her. Upon opening and recharging the counterfeit cellphone Gin's spirit comes alive. May unnoticeably brings home the counterfeit cellphone knowing that she had seen Gin's ghost. She slowly figures out that the counterfeit cellphone is somehow connected to Gin's spirit coming alive. May's curiosity gets the better of her and she decides to recharge the counterfeit cellphone again just to see if Gin will come out again. After May finds out that she is the only one that can see or hear Gin and that Gin cannot venture far away from the counterfeit cellphone, Gin uses May's responsibility for her death to have her take her to GSZ Architects Limited's office because she wants to see Michael. Upset by the new supposed women in Michael's life and after seeing Michael's heartfelt message to her, Gin uses May to communicate with Michael and her loved ones.
In order to still be by Michael's side, help him through his project and keep at bay the sexy new director Lolita who is tasked with seducing Michael, Gin helps May get a job as the new office manager at GSZ. She coaches May to speak with confidence and provides her knowledge of the architect firm. Michael refuses to hire May at first but takes a chance on her when she reminds him of Gin. May who was only interested in the attractive salary of the position at first begins to take her work seriously when she gets to know Michael better and learns how important his current project is to him. Gin who finds herself able to enter May's body uses this advantage to physically connect with Michael. However, because of this physical contact between May and Michael the two starts to develop feelings for each other. But Gin's hard work to built up May's reputation at GZS is soon threatened when May's ex con-artist boyfriend Wong Tai-lung gets a job at GSZ and has ulterior motives.
May's ex-boyfriend working at GSZ is the least of her problems. She does her best to withhold her growing feelings for Michael since she knows how much Gin loves Michael and don't want to offend her. Michael who is in love with May does not make it any easier for her when he finds excuses everyday to have her work overtime at the office with him. Also with rumors of the office being haunted, May is worried that Gin's ghost has been discovered. In order to pay off their debts, head of marketing's Charlie and head of human resource's Lai Hei-wo has been stealing and selling blueprints illegally. They let everyone believe the office is haunted so the office will be empty after work hours. Wong Tai-lung discovers Charlie and Hei-wo's deception and blackmails them for a cut of the profit. Hugo who also discovers Charlie and Hei-wo's deception, with the help of IT specialize Ngai Tit-man bands together with Charlie and Hei-wo to oust Tai-lung out of GSZ in order for Hugo to get the biggest cut of the profits.
Gin discovers Michael's feelings for May and turns against May by telling her that she is a slut who seduced Michael since Michael would never fall in love with a women like her. Gin also reminds May what a loser she use to be, and that all the expensive clothes, handbags, luxury apartment and high level job she has now was all given to her by Gin. With Gin's hurtful words, May gets easily persuaded by Hugo to have her hand over Michael's designs to him. Tai-lung uses pictures of when he and May were together to extort money from her. Once she pays him to retain the pictures he also tells her of Charlie and Hei-wo's deception. May finds out Hugo is also in on the deception and tries to save Michael's career by deleting the stolen designs from Hugo's computer, but May gets electrocuted into a coma in the process. Hugo tries to frame May on his devious plans but Ngai Tit-man. who doesn't want to be part of Hugo's deception anymore tells the truth to the authorities.
With the help of Tit-man, May's family and co-workers, they try to find her spirit that has been electrically wondering around Hong Kong. Gin finally sees how much May means to Michael and starts to let go of her feelings for him. When they find May's spirit she doesn't remember who she is, with Gin's words and the appearance of Michael she regains her memory, but then Michael gets into a near-death accident and both Gin and May must use their spiritual powers to save him. May, who earlier used her spiritual powers, cannot return to her body; Gin helps her and gives her blessing to May and Michael before disappearing into thin air.
Five years later Hugo and Charlie are serving prison sentences with Wong Tai-lung as their jail cell boss. Lai Hei-wo, who just got released from prison, is the new office assistant at GSZ. Ma Mei-ching is the new head of human resources. Charlie's three Angels co-manage the marketing department. Lolita and Ngai Tit-man are a couple who are in a serious relationship. May is head management, calling the shots at GSZ. Michael's design is finally constructed and he gets the award that he has sought after for many years. Michael and May are also a happily married couple with a daughter. As the three prepare to go to bed it's revealed that their daughter is the reincarnation of Gin