Jennie and Michael Logan move into a renovated Victorian house in an effort to repair their strained marriage. Under a dust cover in the attic, Jennie finds a lovely cream-colored vintage dress from the 1890's. She decides to have the tear in the shoulder repaired and wear the dress while entertaining. The first time she wears the dress, she is stricken by dizziness and passes out. When she comes to, she recognizes the attic of her home but it is now an artist's studio. She creeps to the door and hears agitated voices downstairs. A man is shouting "Pamela! Pamela!" Then she passes out again and awakes in her own time. That night she and Michael are awakened by the sound of breaking glass. Something has broken the glass in the door of an antique cabinet. Michael suggests it is because the glass is so old. He sweeps it up and puts it into the trash can.Wanting to find out more about the house, Jennie visits the local historical society. Mrs. Bates, the director, tells her that the house was once owned by an artist, David Reynolds. In 1899 he married Pamela Harrington, daughter of a wealthy and influential man. She was killed the day after the wedding and her father blamed David. Rumor had it that David had seen Pamela's ghost several times. He was later found dead of a gunshot wound and no one ever knew what really happened. Some said Mr. Harrington had him killed, others said it was the woman he had taken up with after Pamela's death. Mrs. Bates shows Jennie the only painting by David Reynolds that had survived. Jennie is shocked to see that the woman in the painting resembles her and is wearing a cream-colored dress similar to hers. Mrs. Bates suggests that she talk to "Aunt Betty" Wilkins, a century-old woman who knows a lot of the town's history. Aunt Betty isn't really Mrs. Bates' aunt but everyone calls her that because she has done so much for the town.The Logans entertain their friends and Jennie wears her dress. The women discuss the possibility of the past, present, and future times all existing at once and if one knows how, one can travel between them. The men scoff at the idea and everyone decides to go for a walk. Jennie sends them on ahead and goes to get a hat she bought especially to wear with the dress. But again she has a dizzy spell and loses consciousness. This time she finds herself on a dirt road near her home. A young man driving a team of horses spots her and begins shouting at her to wait. But Jennie is afraid of him and runs away. She regains consciousness in her own time.Confiding in Michael is not a good idea as he tells her it is a fantasy. He thinks she's making it up to get even with him for having an affair. He even suggests that she should see a psychiatrist. But Jennie knows her experiences are real. She is sure the man is David Reynolds and obviously she resembles his dead wife. On her next trip into the past, David and his dog are in a boat on the lake and she is on the shore. The same thing happens, he begins shouting "Pamela!" and she runs away. Michael finds her lying in the road, sobbing incoherently. This time she agrees to see a psychiatrist.Dr. Lauren believes that Jennie has created a fantasy man who is perfect and lacks Michael's shortcomings. His affair is at the root of the problem. Even though Jennie has forgiven him, she no longer trusts him. In a private conversation with Michael, Dr. Lauren suggests that he be a good husband, kind and supportive.From this time on, Jennie begins to pull away from Michael. As soon as he leaves for work, she goes to the attic and puts on her dress. Losing her fear of David, she introduces herself and says she is a visitor from the city. David tells her about Pamela and how he thought he was losing his mind each time he saw Jennie because they look so much alike. It was he who broke the glass in the cabinet, on the night of Pamela's death. As soon as it is time for Michael to come home, Jennie bids David farewell, walks down the road, and returns to the present.Michael tries to rekindle their marriage but Jennie remains elusive. David consumes her every waking thought. At last Michael suggests that she visit her friends at Fire Island for the weekend. Jennie sees this as a golden opportunity to spend more time with David.Pamela had an older sister, Elizabeth, who was in love with David. She and her boyfriend drive out to the Reynolds house, bringing a picnic lunch. David introduces her to Jennie and Elizabeth is obviously not pleased. But she insists that Jennie remain and share the picnic. Elizabeth reveals that she and David were a couple until Pamela returned home from a finishing school and stole him away. Later, David assures Jennie that he was never in love with Elizabeth and that she read more into it than he intended.Mr. Harrington has hired detectives to watch David and he runs them off with a shotgun. His father-in-law still believes that David was responsible for Pamela's death. Jennie feels he is in real danger but he shrugs it off. He begins a painting of her and asks her to wear the same dress. This is the portrait that eventually wound up at the historical society.Jennie pays a visit to Aunt Betty in order to find out more about what happened to David. The elderly woman mutters that she is sorry. Her nurse cuts the visit short and Jennie learns nothing.Michael gives Jennie a butterfly pendant to wear with her dress. She is charmed and says she will keep it always. But she refuses to admit that her time-travel is a fantasy. Michael catches her rummaging through the trash for the glass shards from the cabinet, then kissing them.David learns that Jennie is married but she reassures him that she is leaving her husband. He asks her to go away with him. She agrees but says it must be soon. Mr. Harrington is an ever-increasing threat, which David still does not take seriously. Even when the elderly man tries to horsewhip him, David feels he is just a grieving father. But then Mr. Harrington challenges David to a duel on the night of the town festival to welcome the new century. Jennie senses that this is how David was killed and is frantic to stop it. She tells Michael that she is returning to the past to be with David. She no longer cares to live in the present. He takes her more seriously than before and asks how he will ever know what happened to her if she just disappears. She assures him that she'll find a way to break through and let him know.On another visit to the historical society, Jennie finds the dueling pistols belonging to Mr. Harrington. One of the employees shows her how easy it would be to tamper with the sights. On the night of the festival, Jennie sneaks into the Harrington home while they are getting ready. The pistols are displayed on a table. Jennie adjusts the sights on each one, hoping both David and Mr. Harrington will miss.At the festival, Jennie and David dance, very much aware that the Harringtons are watching them. Then Jennie has a horrible thought. What if the rumor that David was killed by the woman he was seeing was true? That would mean she killed him. Jennie decides to return to the present until after the duel. David protests but she assures him she will soon return.At home, the telephone rings. It is Mrs. Bates asking that Jennie come immediately to Aunt Betty's house. A startling discovery has been made. Jennie rushes over and learns that Aunt Betty's birth certificate has been found. She was born Elizabeth Harrington. Jennie is shocked to realize that the old woman in the bed was the Elizabeth she had known in 1899. Aunt Betty reveals that it was she who shot and killed David Reynolds because he rejected her. Earlier that day she had paid him a visit and confessed her love. He was quite rude and told her he had never loved her and never could have. She said that if her father missed shooting David, she would not miss. After David's death, she lived in Europe for many years, only returning after her father's death. Obviously she recognizes Jennie and wants her to save David. After learning the location of the duel, Jennie rushes home. There is only a short window of time to return to 1899. But Michael is waiting for her, the dress clutched in his hand.Unbeknownst to Jennie, Michael had called her psychiatrist. Dr. Lauren is alarmed at Jennie's wish to no longer live in this world and thinks she is suicidal. She recommends immediate committal to prevent Jennie from harming herself. Believing that Jennie is at Fire Island, Michael went to get her and learned she had never been there at all. He then decides that Jennie is having an affair, not with a man in the past but someone very real and present. The first thing he intends to do is burn the dress. Jennie grabs it out of his hand, tearing the shoulder, and runs to the attic. Michael succeeds in breaking down the door but it is too late. Jennie is lying dead on the bed, wearing her dress and butterfly pendant. She arrives back in 1899 just as the duel is starting. David fires deliberately at the ground, then tosses his pistol aside. Realizing he could not shoot an unarmed man, Mr. Harrington lowers his pistol. Then Elizabeth steps out of the shadows, holding a gun. Jennie screams and rushes at David to push him out of the way. After the funeral, Michael decides to sell the house and move back to the city. He leaves Jennie's dress in the attic and covers it with the dust sheet. The moving men ask what he wants done with the paintings they found in a corner. Michael is not aware of any paintings but he instantly recognizes Jennie. David has painted her and their three children. In each painting she is wearing the butterfly pendant. At last Michael realizes all she told him was true, that somehow she really had gone back in time. Tears stream down his face.