In 1972, college theatre student Richard Collier celebrates the debut of his new play. During the celebration, an elderly woman places a pocket watch in his hand and pleads, “Come back to me.” Richard does not recognize the woman, who returns to her own residence and dies in her sleep that same night.
Eight years later, Richard is a successful playwright living in Chicago. While struggling with writer’s block, he decides to take a break from writing and travels to the Grand Hotel on Mackinac Island. While exploring the hotel’s hall of history, he becomes enthralled with a vintage photograph of Elise McKenna, a beautiful and famous early-20th century stage actress. Upon further research, he discovers she is the same woman who gave him the pocket watch. Richard visits Laura Roberts, Elise’s former housekeeper and companion. While there, he discovers a music box that plays the 18th variation of Rhapsody on a Theme of Paganini, his favorite musical piece. Among Elise’s personal effects is a book on time travel written by his old college professor, Dr. Gerard Finney. Richard becomes obsessed with traveling back to 1912 and meeting Elise, whom he has fallen in love with.
Richard seeks out Professor Finney, who believes he briefly time traveled through the power of self-suggestion. Finney warns Richard that such a process would leave one very weak physically, perhaps dangerously so. Richard is determined to try. Dressed in an early 20th-century suit, he removes all modern objects from his hotel room and attempts to will himself to 1912 using tape-recorded suggestions. The attempt fails because he lacks real conviction, but after finding a hotel guest book from 1912 containing his signature, Richard realizes he will eventually succeed.
Richard hypnotizes himself again, this allowing his absolute faith in his eventual success to serve as the engine that transports him back to 1912. Richard finds Elise walking by the lake. Upon meeting him she asks, “Is it you?” Her manager, William Fawcett Robinson, abruptly intervenes and sends Richard away. Although Elise is initially uninterested, Richard pursues her until she agrees to accompany him on a stroll the next morning. During a boat ride, Richard hums the theme from the 18th variation of opus 43, a tune Elise has never heard before as it has yet to be written. Richard asks what Elise meant by, “Is it you?” She reveals that Robinson has predicted she will meet a man who will change her life, and that she should be afraid. Richard shows Elise the pocket watch she will give him in 1972.
Richard attends Elise’s play where she gives an impromptu monologue dedicated to him. During the intermission, Elise poses formally for a photograph but seeing Richard, breaks into a radiant smile. It is the same image Richard saw 68 years later. Afterward, Richard receives an urgent message from Robinson requesting a meeting. Robinson wants Richard to leave Elise, saying it is for her own good. When Richard says he loves her, Robinson has him bound and locked inside the stables. Robinson then tells Elise that Richard has left, though she does not believe him and professes her love for Richard.
Richard wakes the next morning and frees himself. The acting troupe has already left for Denver, though Elise has returned to the hotel to find him. They go to her room and make love. They agree to marry and Elise promises to buy Richard a new suit, as his is about a decade out of style. Inside one of the suit pockets, Richard discovers a penny with a 1979 mint date. This modern item breaks the hypnotic suggestion, pulling Richard into the present as Elise screams in terror.
Richard awakens back in 1980. His attempts to return to 1912 are unsuccessful. After wandering the hotel grounds despondently, he returns to his room and, physically weakened by the time travel and brokenhearted, dies in despair. His spirit is drawn into the afterlife, where he is reunited with Elise