When the beautiful and glamorous Helen is deserted by her lover, she marries the kindly Martin McMahon and moves to the small village of Lough Glass. Although Martin and Helen have two children, Helen still pines for Louis, the man who broke her heart.
Helen seems restless and unhappy living in Lough Glass. Then one day, Helen disappears, leaving behind only a note for Martin. Kit, Helen and Martin's 13-year-old daughter, finds this letter, and burns it without opening it. Kit knows that her mother was unhappy and assumes that her mother has committed suicide. A suicide note would mean that her mother could not be buried in 'consecrated' ground according to Catholic tradition. However, Helen hasn't committed suicide. Rather, she decided to run away to England with her former lover.
Kit McMahon struggles to grow up without her mother and with the stigma of her mother's death. While Kit has many friends and mentors to help her grow, she forges a close relationship via letters with Lena Gray. Lena Gray claims to be a close friend of Helen. However, Lena Gray is really Helen herself. The story then traces the fallout of Kit finding out that her mother isn't dead and is Lena Gray.