Terry Gionoffrio, a young dancer from Nebraska now working in New York City, sustains a serious ankle injury mid-performance in a Broadway production of Kiss Me, Kate, causing the show to be stopped. She becomes known as "the girl who fell" and although unable to perform as she previously did, continues to unsuccessfully audition for dancing parts. After auditioning for Broadway producer Alan Marchand, she follows him home to the Bramford apartment building and becomes sick. She is befriended by Minnie and Roman Castevet, an elderly couple who live in the Bramford's apartments and who offer her an apartment down the hall rent-free, which they explain as something they have done before to help someone who needs it. Unpacking, she comes across a ballet slipper labeled Joan Cebulski.
The Castevets invite her for cocktails at Alan's apartment, but when she shows up, she discovers the Castevets have cried off and she is the only guest. After a drink, she becomes disoriented. After a frightening dream, she wakes in bed in Marchand's apartment. He implies they had sex and tells her she made the chorus for his show.
Terry meets more of the neighbors, who take an interest. One woman, Lily Gardenia, gives her a salve for her ankle, and she has another frightening dream, but in the morning her ankle is markedly better. Another, Dr. Sapirstein, an obstetrician, gives her his card. The Castevets give her a talisman necklace for Christmas.
After experiencing morning sickness, she visits Dr. Sapirstein and discovers she is pregnant, and the news is soon known to Alan and the Castevets.
Terry discovers a secret passageway into Lily's apartment and finds a note and a grimoire. She steals the grimoire and finds a drawing of her talisman in it along with a photo of a chained woman giving birth to a demon.
Terry experiences pain and calls Dr. Sapirstein, telling him she thinks there's something wrong with her or the baby. He tells her to pack a bag and come in, and when she asks why she would need a bag, he tells her she may be experiencing perinatal hysteria and need to be admitted for her own protection and that of the baby.
Terry flees, leaving the talisman behind. She finds Joan Cebulski's name in an old Playbill and visits the theater; the manager tells her Joan left six months earlier, promising to be back for her belongings the next day. In Joan's suitcase, Terry finds a rosary and a bible with Revelation 12:9 underlined.
Terry goes to a back-alley abortionist, accompanied by Annie; Terry involuntarily kicks the abortionist as she starts the process, and the woman has a seizure. Terry tells Annie she has to deal with the pregnancy "on her own".
Back at the Bramford, she finds a temple with murals and tools of religious ritual in a sub-basement. Alan appears and tells her this is where she was impregnated. Alan taunts her, and she stabs him with an engraved athame. A horned figure appears, and she flees. Finding Minne and Roman in her apartment, she tries to stab herself in the stomach but falls to the floor, writhing in pain. Roman tells Terry her son will be satan's heir and change the world. He and Minnie take her to the rest of the group, who welcome her. Minnie replaces the talisman around Terry's neck and Roman declares God dead and 1965 the year one. He raises a toast, "Hail, Satan", which Terry joins in on. She begins to dance artistically to Be My Baby, and reaching the window, throws herself out to her death. As Minnie and Roman approach the scene, they see Rosemary and Guy Woodhouse being interviewed by police.
