A patient at a hospital is stalked by an obsessive stalker from her youth.
At Susan Jeremy's house in 1961 on Valentine's Day, Susan and Young Dave are playing. Harry looks in Susan's window and watches her and Dave playing. Harry drops off a letter at Susan's front door and knocks on the door. Susan takes the letter and Harry watches as Susan opens the letter and she and Dave laugh at it and Dave crumples it up and throws it away. Susan gets some cake and when she returns she finds Dave dead hanging from the coat rack and Harry staring at her.
19 years later, Susan is leaving work when Eva runs up to her and hugs her. Tom walks up and asks Susan to take Eve early, but Susan tells him she has to go to the hospital to get her test results. Jack pulls up in his car and Susan leaves with him. Jack drives her to the hospital and before she gets out, mentions how he heard that particular hospital had a patient that ran a muck last year. As she is walking in, someone in a surgical mask, The Doctor stares at her from inside the hospital. Susan walks up to the Desk Nurse and tells her she is there for the results of her tests. As Susan is waiting, The Janitor stares at her intently. The Desk Nurse tells Susan to go to room 809 on the 8th floor. As Susan is waiting in the elevator, she looks over and sees Hal leaning against the elevator with a red substance around his mouth. Hal takes a bite from a hamburger and Susan tells him he should be more careful as the ketchup from his burger spills on her shoes. The Doctor walks over to a framed photo of Susan as a kid and caresses it.
Susan accidentally goes to the 9th floor and when the door opens is told the 9th floor is being fumigated. The Doctor pulls a lever and the elevator stops. A voice comes over the system asking Dr. Jacobs to come to the 9th floor. She takes the stairs and is stabbed to death by The Doctor. The Doctor goes to Dr. Jacobs' office and takes the test results from Susan and switches them with other test results. Susan goes to Dr. Jacobs' office, but no one answers the door. While The Janitor is storing CPR dummies on the 9th floor, he finds Dr. Jacobs' body and then tells The Doctor, who eventually kills The Janitor by shoving his face in a chemical solution. Susan calls Tom while Dr. Davidson stares at her, but Tom doesn't answer the phone initially. Eva says it might be Susan and asks him to talk to Susan, but when he picks up the phone, Susan has already hung up. Dr. Beam walks up to Susan and asks if she needs help and she tells him she is looking for Dr. Jacobs. He directs her to the doctor's lounge and Susan talks to Harry and asks him if he can get her results for her, but he says he can't without Dr. Jacobs' approval. She asks him please and they go to Dr. Jacobs' office and as Susan is signing her receipt, Harry looks at her results and tells her another doctor needs to co-sign them.
They go to Dr. Saxon's office who is taking off a surgical mask at the time. Dr. Saxon looks at Susan's results and afterwards leaves his office with her results. Susan calls Tom's house and Eva tells her, Tom left. Nurse Dora and Nurse Kitty open the door to Dr. Saxon's office and ask Susan to come with them. They take her back to see Dr. Saxon who tells Susan another round of tests will be needed. Dr. Saxon has Susan get undressed and Dr. Beam walks in and tells Dr. Saxon he can't find Dr. Jacobs. Dr. Saxon shows Dr. Beam, Susan's x-rays and Dr. Beam leaves. Dr. Saxon then examines Susan. As Dr. Saxon is examining Susan, Hal watches through the window in the door until he is caught by Nurse Kitty, but then returns when Nurse Kitty leaves. Dr. Saxon takes a blood sample and Nurse Kitty takes Susan to a room where Mrs. Edelman, Mrs. Fedrow and Mrs. Parry are currently at. Nancy says hello to Suzy and invites her to get some coffee, but Suzy tells her she has to complete typing up a report on Susan. After Nancy leaves, The Doctor stabs and kills Suzy and types up new results for Susan.
Harry brings Dr. Saxon, Susan's results and he and Dr. Beam look at the results and they mention Susan is dying. Nancy finds Suzy dead and is then strangled to death by The Doctor. Dr. Saxon walks into Susan's room with Nurse Dora and Nurse Kitty and tells her they will have to keep her in the hospital. Mrs. Parry walks over to Mrs. Fedrow and Mrs. Edelman and tells them the doctors said Susan is very sick. After Mrs. Fedrow mentions how young Susan is, Mrs. Edelman says Susan is young on the outside but rotten on the inside. Susan runs out of her room and runs into Harry and tells him she has to get out of the hospital. He asks how long she has been Dr. Jacobs' patient and he agrees to look at her files. He looks at her files and tells her she should be released within the hour and someone is messing with her diagnosis. Jack goes to the hospital to look for Susan and the Desk Nurse sends him to the 8th floor. Jack speaks to Ned who speaks with Nurse Kitty and tells Jack, Susan is under observation. Jack goes into Susan's room and she tells him the hospital won't let her leave. She tells him she wants to leave and as they are leaving the hospital they are blocked by Dr. Saxon, Nurse Kitty and Nurse Dora and Dr. Saxon orders Susan brought back to her room and he tells Jack he will tell him more in his office. The PA systems tells Jack to answer the phone and he is directed to room 911. He runs into Hal and Mrs. Fedrow, Mrs. Parry and Mrs. Edelman who mistake him for Dr. Jacobs. When he goes to room 911 he finds the body of Suzy and he is killed with a medical saw.
Susan is woken up when The Doctor leaves her a present which has the head of Jack inside the box. She runs for help and is found by Dr. Saxon and Nurse Kitty and she tells them someone killed Jack. They take her back to her room and the box this time has cake inside, similar to the one she received as a child on Valentine's Day. Susan tells Dr. Saxon that Harry looked at her files and Dr. Saxon tells her he will check on them. After Dr. Saxon and Nurse Kitty leave, Susan walks out of her room again to try and escape. She hears The Doctor coming and sees him with a hatchet and hides until he walks by. She walks down the stairs and is stopped by Hal who tries to kiss her and she pushes him away and walks into the Archives room. She sees Dr. Saxon look at her file and watches as The Doctor kills him with the hatchet. Susan goes screaming down the hallway and is grabbed by Ned, Nurse Dora and Nurse Kitty and brought back to her room and strapped down to a bed. Dr. Beam walks in and they tell him Susan is having a hallucination as she yells Dr. Saxon was killed. As Nurse Dora is walking down the hallway, The Doctor charges her carrying a sheet and covers her with it and injects her with something that kills her. As Dr. Beam is looking at Susan's chart again, he is stabbed through the back of the throat. The Doctor goes into Susan's room and drags her bed with him, he takes her to the 9th floor and puts her on an operating table. She pulls away his medical mask revealing The Doctor to be Harry and he tells her he wants her heart, which he always wanted. Mrs. Edelman, Mrs. Fedrow and Mrs. Parry walk into the hallway and confuse Harry for Dr. Jacobs and Susan stabs Harry in the stomach and runs away. Harry chases her and grabs her leg at one point and Susan spills a beaker full of flammable liquid on him. She runs to the roof and lights Harry on fire, and Harry plummets to his death when Susan walks to the edge of the roof and Harry lunges at her. Susan then walks out of the hospital and is greeted by Eva and Tom.