A young woman falls in love with the son of an old family enemy.

In turn-of-the-century England, John Carteret still mourns the death of his fiancée Moonyean Clare, who died on their wedding day in 1868. As John and Moonyean were taking their marriage vows, Jeremy Wayne, a close friend of Moonyean's who had wanted to marry her himself, aimed his pistol at John in a drunken, jealous rage. When the gun discharged, however, the bullet hit Moonyean, who died promising John that she would come back to him. Now John spends his days talking with her spirit in the garden, the place where they were the happiest. Over the years, she has become his only comfort and remains as beautiful as ever. John's friend, Dr. Owen, thinks that John lives too much in the past, and asks him to care for Moonyean's recently orphaned five-year-old niice Kathleen. John is reluctant, but when he meets the sweet child, he cannot send her away and becomes a devoted guardian. By 1915, the child has grown into a beautiful young woman, the image of her late aunt and the light of John's life. She has many suitors, none of whom interest her, until one rainy afternoon when she and her friend Willie Ainley take refuge in a deserted mansion. There she meets the current owner, handsome American Kenneth Wayne, who is Jeremy's son. After Moonyean's death, Jeremy ran away to America and married. Kenneth, who has just come to England to fight in the war, knows nothing of his father's crime, nor does Kathleen, and the two fall in love. When Kathleen tells John about Kenneth, however, he tells her the tragic story of Moonyean, and makes her promise never to see Kenneth again. Because she and Kenneth have fallen so deeply in love, she cannot give him up, however, and continues to meet him in secret. The night before Kenneth is to report for active service, Kathleen tells John that she is going to marry Kenneth that night, and John asks her to leave. Because Kenneth is worried that Kathleen might become a widow, and he knows how much she cares for her guardian, he sends her home without marrying her. After the war ends, Kathleen waits for Kenneth's return and finds him one day in the Wayne house. Because he has been severely wounded in the war, Kenneth does not want to be a burden to Kathleen and pretends that he no longer loves her. Shattered, she returns home, where Dr. Owen tells John what has happened. Walking in the garden, John is joined by the spirit of Moonyean, who tells him to forget the past and help the young lovers. He then summons Kenneth and brings him and Kathleen together so that they will be able to marry and go to America. That evening, after Kathleen and Kenneth have gone, John plays chess with Dr. Owen and apparently falls asleep. When the doctor quietly leaves, Moonyean again appears and takes John's hand. John's body remains in the chair, but his youthful spirit arises and he walks away, hand-in-hand with his beloved Moonyean.