George and Mary are childhood sweethearts in Suffolk's Greenwater Broad. Despite a prediction from Mary's grandmother, old Mrs Dermody, that their two destinies are inextricably linked, George's father disapproves. He separates them by taking his family to America where he subsequently dies. George and his mother return to England where she marries Mr Germaine, a rich suitor she had known before her first marriage.

George has no way of tracing Mary and leads a dissolute existence which prematurely ages his appearance. He reforms, trains to become a surgeon, and takes up an appointment in India. After being wounded in the shoulder, George returns to England where he inherits his step-father's fortune and estate in Perthshire. There is a condition that he must change his name to Germaine.

Mary, meanwhile has suffered a serious illness which has totally changed her looks. She has married a Dutchman called Van Brandt and is also living in the same part of Scotland. When Mary discovers that her marriage is bigamous, she throws herself into the river but is saved by George.

They fail to recognise each other but develop an almost telepathic attraction. George sees an apparition of Mary calling him to Edinburgh. They meet and he learns that Mary had dreamed of him at exactly the same time. She declines his help and he next sees her in London, still in company with Van Brandt. George proposes marriage but Mary, who has a baby daughter, refuses, for fear of spoiling his life.

George goes away to the Shetlands to forget but injures his wounded shoulder. He is nursed back to health by the mysteriously disfigured Miss Dunross to whom he confides his story. On his recovery, he sees another apparition which leads him to Mary and her child, starving in lodgings near St Paul's. Van Brandt is in a debtors prison and George helps by paying off the debts. He again proposes but Mary goes abroad with Van Brandt.

George's mother dies shortly after. Alone and in despair, he returns to Suffolk where he contemplates suicide. He is saved by a third apparition which takes him to the ghost town of Enkhuizen on the coast of Holland. Van Brandt has embezzled money from his old company and abandoned Mary and her child. When she refuses marriage for a third time, George resolves to drown himself and take Mary with him. At the last moment she sees a childhood memento which she once made for him. They finally recognise each other and their two destinies are reunited. Newly married, they are ostracized from society because of malicious scandal. They leave England to start a new life in Naples.